Category Archives: fossils

Episode 116: Amazing Hoofed Animals

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This week we’re taking a bunch of listener suggestions and learning about a bunch of amazing hoofed animals! Thanks to Richard E., Pranav, Grady, and Simon for all their suggestions!

A pronghorn antelope, which is NEITHER AN ANTELOPE NOR A DEER:

A musk deer, which is NOT ACTUALLY A DEER AND ACTUALLY LOOKS A LOT LIKE A KANGAROO OR RABBIT WITH FANGS:

A chevrotain, or mouse deer, which is ALSO NOT A DEER AND LOOKS LIKE A RODENT FRANKLY (lesser mouse deer on left, water chevrotain on right)

A mama pudu with her baby, WHICH ARE DEER:

A goat eating poison ivy like I told you they do:

A horse eating watermelon, because it’s adorable:

An entelodont, AKA HELL PIG:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week I wanted to get back into some of the excellent suggestions I’ve gotten from listeners. I looked over the list, hoping that a theme would present itself…and one did. Sort of. This week let’s learn about some interesting hoofed animals, some of them living today, some extinct. Thanks to Richard E., Grady, Pranav, and Simon for the suggestions I used in this episode, in no particular order.

First, Richard asked about the differences between deer and antelope. This is an excellent question, obviously, because I’ve been sitting here staring at the screen thinking, “Well, I know they’re not members of the same family but how closely are they related?” So let’s find out. And I’ll warn you now, this gets complicated—but in an interesting way.

Antelopes are bovids, related to cows, sheep, and goats. Deer are cervids. Both groups are related, but not very closely. They’re both members of the order Artiodactyla, the even-toed ungulates, because they have hooves with two toes, called cloven hooves.

At first glance, many antelopes look a lot like deer. But antelopes have horns, not antlers, and the horns are permanent. Deer have antlers, which they shed and regrow every year. And antelope horns, like the horns of goats, sheep, and cattle, don’t branch, whereas deer antlers almost always do.

So far this is pretty straightforward. But now things get complicated. Antelopes are native to Africa and Eurasia while deer live throughout the world. But there are deer that aren’t deer and there are some antelopes that aren’t antelopes. Uh oh. We’d better figure this out.

One thing to remember is that the group of bovids referred to as antelopes have all been lumped together in what’s sometimes referred to as a wastebasket taxon. Basically that means that the animals in that taxon didn’t really fit anywhere else, so scientists grouped them together for the time being. If a bovid is clearly not a cow, a sheep, or a goat, it’s put in the antelope group.

There aren’t any antelopes living in the Americas today. If you happen to live in the western part of North America, you probably just sat up and said, “Hey, you forgot about the pronghorn!” But the pronghorn antelope…is not an antelope.

Sure, the pronghorn looks like an antelope. It’s deer-like, runs extremely fast just like antelopes, and has short black horns. But look at those horns. It’s called a pronghorn because the horns of the males have a prong, or branch, so that the horn is shaped sort of like a Y, with the front branch of the Y shorter than the other, and the longer branch of the Y having a sort of hook at the top. Remember how antelopes only ever have unbranched horns? That’s a clue that the pronghorn isn’t an antelope.

But the pronghorn also isn’t a deer. Its horns are horns, not antlers, and it keeps its horns throughout its life instead of shedding them every year. Except that it kind of does shed part of the horn every year, the sheath. The inside of a horn is bone that grows from the skull, but a sheath of keratin grows over it. If you’ve ever seen an old-fashioned drinking cup made of horn, it was made of a horn sheath, usually from a bull. Most horned animals keep the sheath, which grows as the horn grows underneath, but the pronghorn male sheds the sheath of his horns every year and then grows new ones.

So what is the pronghorn related to? Are you ready? It’s related to the giraffe! I’m not even making this up. It’s not closely related to the giraffe, though, and it’s the only living member of its own family. I think I might have to revisit the pronghorn family in its own episode one day, so for now I’ll just point out that the pronghorn is the second-fastest land animal alive, with only the cheetah able to run faster. The pronghorn can run 55 mph, or 88 km/h, for half a mile, or .8 km.

So the pronghorn isn’t an antelope or a bovid, but it looks like an antelope because it shares a similar habitat and ecological niche. You know what that means! Yes, the pronghorn looks like an antelope due to convergent evolution.

Next, let’s talk about those deer that aren’t deer. Are they related to giraffes too? Are giraffe relatives taking over? No and probably no.

There are two groups of deer that aren’t actually deer. The musk deer of Asia and the chevrotains of Asia and Africa are related to deer but they’re also related about as closely to bovids like antelopes. They’re also not that closely related to each other. Just looking at them tells you that they’re different, since they don’t look like ordinary deer.

There are seven species of musk deer alive today, and while musk deer used to live throughout Eurasia, these days they’re restricted to Asia, especially the Himalayas. They’re small, no more than two and a half feet high at the shoulder, or 70 cm, with hind legs that are longer than their front legs. The back is humped more like a rabbit’s than a deer’s. This allows them to run extremely quickly. They also don’t have antlers or horns, but males do have fangs that they use to fight other males. Fangs, people! Deer-like animals with fangs! They’re not small fangs, either, they’re basically slender tusks that grow down from the upper jaw and can be up to four inches long, or 10 cm. The tusks break easily, but they grow continuously, especially during mating season.

All species of musk deer are endangered due to overhunting, especially for the male’s scent gland, called a musk gland. This gland has been used in perfumes for centuries. These days most perfume-makers use a synthetic musk instead, but the musk deer is still being hunted for its musk gland. The male uses his musk to mark his territory, which warns other males away and attracts females.

Musk deer kind of look like if you tried to draw a kangaroo but you got mixed up halfway through and forgot you were drawing a kangaroo and decided to draw a rabbit instead. Then you added fangs.

The other deer that isn’t a deer is the chevrotain, also called the mouse-deer. There are a number of chevrotain species and they all look more like little rodents than deer. They’re all small and have bulky, rounded bodies but short spindly legs. Like musk deer they have long canine teeth instead of horns or antlers. Female chevrotains have these fangs too, but they’re longer in males and are angled outward like tiny pig tusks. Males use the teeth to fight each other. Most chevrotains are brown or reddish-brown with white streaks on the throat and sometimes face.

Some species of chevrotain like water and, like the marsh cottontail rabbit we learned about last week, will submerge in the water to hide from predators. It can hold its breath for up to four minutes. It can even walk on the bottom of the stream bed, grabbing plants with its teeth to help keep it from being swept away by the current.

The smallest chevrotain is the lesser mouse-deer, which lives across southeast Asia. It’s only about 18 inches tall at most, or 45 cm, and weighs less than 5 pounds, or 2 kg. But the smallest deer was a suggestion by Simon, and that’s the pudu. Specifically, it’s the northern pudu with the scientific name Pudu mephistophiles. I don’t know how it got this name since it’s only 14 inches tall, or 35 cm, and looks inoffensive and not devilish at all. It’s reddish-brown with big eyes, rounded ears, and little stubby antlers that only grow around four inches long, or 10 cm. It lives at high altitudes in the Andes Mountains in South America. It sheds its tiny antlers every year and regrows them, but unlike most other deer, its antlers don’t have any branches.

Because the pudu is so small, it can have trouble reaching the plants it eats. Like other deer, it’s a browser instead of a grazer, eating leaves, twigs, fruit, seeds, and bark, but not grass. It stands on its hind legs to reach leaves, but if it finds a bendy sapling, it will push it with its forelegs until the tree is bent down far enough for the pudu to reach its leaves and twigs.

The pudu is territorial and travels on little trails it makes through its territory. The southern pudu, which is only slightly larger than the northern pudu, will also build tunnels in the underbrush so it can travel without being seen by predators.

Unlike the pudu, the chevrotain hasn’t changed much in millions of years and shows primitive traits compared to modern hoofed animals. It actually shares some traits in common with pigs. While pigs are hoofed animals, they’re not closely related to chevrotains. Researchers think the chevrotain retains traits that were once common in early ruminants.

What’s a ruminant, you may be asking. Aha, this is a good question. Ruminants are hoofed animals that chew their cud, and that includes the chevrotain, the giraffe, musk deer, deer, bovids like cows, goats, sheep, and antelopes, and the pronghorn.

As I mentioned last week in the giant rabbits episode, cud-chewing is one way some animals have evolved to extract as many nutrients as possible from plants. Most plant material is tough and can be hard to digest. Ruminants have a complicated digestive system that helps with this. I bet someone at some point has told you that cows have four stomachs, and maybe you didn’t believe them. But they do. Almost all ruminants have four stomachs, or more properly, four specialized chambers that make up the stomach section of the digestive system.

This is how it works. Let’s say a goat is eating poison ivy leaves, which is something they do, and they don’t seem to have any problem with it either. The goat swallows the leaves, which go into the first two chambers of the goat’s stomach, called the rumen and the reticulum. Both these chambers contain lots of beneficial microbes and bacteria, which immediately start to ferment and break down the leaves. As this happens, the food forms into clumps of partly digested leaves called cuds. After a while, the goat regurgitates a cud and chews it thoroughly, further breaking it down, then swallows it and regurgitates another cud to do the same thing, and so on until it’s cudded everything in its rumen. Then it goes to eat some more.

After the cuds have been chewed and swallowed again, they pass through the rumen and reticulum and into the third chamber, the omasum [oh-MAY-sum]. This is where nutrients start to be absorbed. Only tiny pieces of plant are able to pass through the omasum into the fourth chamber, the abomasum [abba-MAY-sum], which is equivalent to our own stomach. This chamber adds acids to the plant material and kicks the digestive process into high gear, pushing everything on into the small intestine, where most of the nutrients are absorbed. Then what’s left of the plants goes on into the large intestine, where water is absorbed from it and the indigestible parts are packed into pellets that are pooped out.

So most ruminants have four-chambered stomachs. But not all of them. You know which ruminant only has three stomachs? That’s right, the chevrotain, the little mouse deer that kind of looks like a pig.

Pigs, by the way, aren’t ruminants. They’re omnivores and only have one stomach.

So with all this information about chewing cuds in your brain, let’s answer Grady’s question. Grady wants to know how horses digest their food.

Are horses ruminants? They eat grass and other plants. The answer is no, horses aren’t ruminants and don’t chew their cud as part of the digestive process. A horse has only one stomach but it still manages to digest grass and other tough plants just fine. This is how it works.

First, the horse chews its food really thoroughly before swallowing. Like ruminants, the horse’s teeth continue to grow throughout its life, since plants wear teeth down. The horse also produces massive amounts of saliva as it chews, and saliva contains an enzyme called amylase that helps start the digestive process. So before a horse even swallows a single bite of grass or hay, that plant material is chewed up into little bits and mixed with lots of saliva.

Oh, in case you were wondering, a male horse has forty teeth while a female only has 36. I do not know why. But ruminants don’t have front top teeth at all, just a bony pad. That helps them trim plants right down to the ground.

After a horse swallows its food, the stomach mixes it with digestive enzymes and acids that break the plant material down even more. A horse actually has a surprisingly small stomach for its body size, but typically food doesn’t stay in the stomach long. It passes into the small intestine and then into the large intestine, where most of the actual digestion takes place. Microbes in the large intestine help break down the plant material so that the horse can absorb it.

The large intestine is sometimes called the hindgut, because it’s behind the other parts of the digestive system. Horses are hindgut fermenters, which means a horse’s food is fermented, or broken down by microbes, in the hindgut, or large intestine. Ruminants are called foregut fermenters because their food is fermented, or broken down by microbes, in the foregut, or the stomach chambers that come before the rest of the digestive system. And if you’re curious, rabbits and hares are also considered hindgut fermenters.

There are lots more fascinating hoofed animals I want to talk about, but I have to stop somewhere. Don’t worry, eventually we’ll learn about some actual deer with fangs as well as antlers, and more about the pronghorn, and lots more. But we’ll finish up this week with a suggestion from Pranav, who wanted to learn about an extinct hoofed animal called the entelodont.

What’s an entelodont? It’s sometimes called the HELL PIG. Why would it be called that? Is it like the little Mephistopheles pudu who must have scared some scientist one day and ended up with a devilish name? Nope, the entelodont is called the hell pig because it was enormous and terrifying. Fortunately for us, it went extinct millions of years ago.

Despite its name, the entelodont isn’t all that closely related to the pig. It’s more closely related to the hippo and to WHALES, because whales and hippos are closely related. But the various species of entelodont were pig-like in many ways. Entelodonts lived throughout much of the world, but let’s look specifically at the biggest entelodont known, Daeodon [DIE-oh-don], which lived in North America up to about 18 million years ago.

Daeodon stood nearly six feet tall at the shoulder, or about 1.8 meters. It had long, slender legs with cloven hooves, and its body was bulky and something like 10 feet long, or 3 meters. It didn’t have a pig-like snout, and in fact its nostrils were on the sides of its nose, which probably helped it track food by scent. It had flared cheekbones with bony protrusions that probably meant it looked a lot like a modern warthog. Its tail was short and small.

Daeodon was an omnivore, which means it would eat just about anything it wanted, and it had the sharp, serrated teeth of a predator. It probably did a lot of scavenging of dead animals, but it could have hunted and killed prey too. Its jaw was so strong it could bite right through bones. And it could run quickly.

So basically, daeodon and entelodonts in general earn the nickname hell pig. It’s probably a good thing they’re not still around. I personally prefer the tiny and harmless Pudu mephistophiles.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 108: Strange Things Found in Amber

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Thanks to Nicholas for suggesting this week’s episode topic! Lots of strange and fascinating insects and other animals are found trapped in amber. So what is amber, how does it preserve animal parts, and most importantly, what have scientists found in amber?

A millipede preserved in amber, one of 450 millipedes discovered in Myanmar amber. Somebody had to count them:

A newly described insect that got its own order because it’s so weird. Look at that triangular head with giant eyeballs!

A mushroom, a hair, and a tiny phasmid exoskeleton, all caught in amber:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

Last month I released an episode about trace fossils, and listener Nicholas wrote me to suggest I also do an episode about amber—specifically, the animals and other items that were trapped in amber and preserved inside it when the amber fossilized. Nicholas also sent me lots of links to really interesting articles!

Amber is the term for fossilized tree resin. If you’ve ever climbed a pine tree and ended up with pine sap all over your hands, which is impossible to get off by just washing your hands and is super sticky and picks up every bit of dirt, you’ll have an idea of what amber starts out as and why it sometimes has insects and other stuff in it. Despite the name pine sap, it’s not actually sap. Sap is the fluid that carries nutrients around to a plant’s cells, sort of like plant blood. Resin is secreted by certain trees and other plants for various reasons, including to protect it from insect damage, to kill fungus, to seal off a broken branch or other injury, and to taste bad so herbivores won’t eat it.

There are different types of amber, because there are different plants that produce resin. We don’t always know what species of plant a particular type of amber comes from, since many are now extinct and can’t be directly studied. Conifer trees evolved around 300 million years ago but became really successful during the Mesozoic around 250 million years ago, spreading throughout the world and dripping resin all over the place. Conifers include pine trees, fir trees, hemlocks, yews, larches, junipers, cedars, redwoods, spruces, and lots of other trees and shrubs that are still widespread today. Some flowering plants, mostly trees, also produce resins. But before conifers evolved and outcompeted them, plants called medullosales lived around the world and produced resin too. Medullosales first appear in the fossil record around 360 million years ago and mostly died out around 298 million years ago. They’re all extinct now.

If your name is Amber, by the way, you are named for fossilized tree resin. That sounds gross, but amber has been prized for millennia as a gemstone. When polished, it can be a gorgeous yellow, gold, or brown, often the color of honey. But some amber is other colors, including red, blue, or green. It all depends on what tree originally produced the resin, its chemical makeup, and how it was fossilized.

So how does the resin fossilize? Sometimes it would drip onto the ground, become buried, and fossilize along with the ground around it. Sometimes the resin-producing tree would fall, become buried, and the resin inside would fossilize along with the wood. Sometimes the resin would drip into water, float to a quiet area or sink to the bottom of the pool or lagoon, and fossilize along with the sand and other sediment that covered it. This is why so much amber is found in the ocean, by the way. Once fossilized, amber floats in salt water—just barely, but enough that on some beaches it’s commonly washed up with the tide. People collect the pieces of amber to polish and sell. Amber can also be burned and often gives off a musky, piney scent that has been used in religious ceremonies.

The reason we’re talking about fossilized plant material in an animal podcast is that amber sometimes has insects or other small animals or animal parts inside it. This happened when it was still resin, which is really sticky. If an ant or bee was in the wrong place at the wrong time, it could be covered with resin and die. Then, if that particular dollop of resin ended up getting protected by sediment at just the right time, instead of weathering away and decaying it might fossilize over millions of years with the ant or bee or whatever inside it. And because the ant or bee was protected from air, water, and bacteria by the resin, and kept in place, the things found in amber are usually mostly intact and include parts of the body that ordinarily never fossilize. It may even help preserve DNA, which ordinarily decays after a matter of thousands of years, although there’s still conflicting evidence about whether this is the case. All this helps researchers study animals that went extinct millions of years ago almost as though those animals were still around.

Substances inside amber are called inclusions, whether they’re something exciting like a spider or just a piece of dirt. Well preserved inclusions, especially pretty ones like flowers, can make the piece of amber extremely valuable. If you want to buy polished amber with an inclusion, though, keep in mind that there are a lot of fakes out there. Make sure to have an expert examine an expensive piece before you spend money on it.

So let’s learn about some insects and other things that have been discovered in amber. I’m going to mention Myanmar repeatedly because it’s a big amber-producing region and the subject of an intensive ongoing study of animals found in the amber. Myanmar is in southeast Asia and was once called Burma.

The oldest organism found in amber are two tiny mites and a fly dated to 230 million years ago. The amber in question is very small, droplets no more than about six millimeters across, found in the Italian Alps. The mites are two different species, both new to science although they have living relations that resemble the ancient mites closely. Both of them ate plants. The fly isn’t as well preserved so researchers aren’t sure what species it was.

A 3 millimeter beetle found in amber dated to 99 million years ago was found in Myanmar. It’s an ancient relative of the modern flat rove beetle that lives under tree bark. But the flat rove beetle lives in South America, with one species from southwestern North America. Comparing the modern beetles with their ancestor gives researchers a closer idea of when the supercontinent Gondwana started to split apart into smaller continents as the landmasses moved slowly across the Earth to their current positions.

The amber found in Myanmar has yielded a lot of interesting information during recent studies. For instance, 450 millipedes! Not all in one piece, of course. The research team used a new type of analysis called micro-CT, which scans the inclusion and creates a highly detailed 3D image which can then be studied without damaging or even touching the amber. This is helpful when the amber pieces are privately owned and only on loan to scientists. Some of the millipede specimens were newly hatched, some fully grown, and include many species new to science.

Another insect found in Myanmar amber dated to 99 million years ago is so unusual that researchers placed it in its own order. To illustrate how rare this is, there are over a million insects described by scientists but they all fit into 31 orders. But now there’s 32 orders. The insect had a triangular head with big bulging eyes, a long flat body, long legs, and no wings. It also had glands on its neck that secreted chemicals that probably helped repel predators. Because of its large eyes and the unusual head shape, it could see almost all the way around it without turning its head. Two specimens of the extinct insect have been found in amber. One of the researchers who described the insect, amber expert and entomologist George Poinar, Jr, said that he thought it looked like an alien’s head so he made a Halloween mask that looked like it. As you do. He said “when I wore the mask when trick-or-treaters came by, it scared the little kids so much I took it off.”

It’s not just insects that are found preserved in amber. One foot and part of a tail from a 100 million year old gecko were found in amber about a dozen years ago. Researchers think the rest of the gecko was probably eaten, possibly by a dinosaur. Even though there isn’t a lot of the gecko to study, there’s enough to determine that it was a genus and species new to science, and that it was probably a juvenile gecko that would have grown up to a foot long if it had lived, or 30 cm. It was only about an inch long when it died, or a bit over two cm. It was stripey and had the same type of toe pads that modern geckos have that allow them to walk up walls.

Another foot, this one from a frog, was discovered in more of the Myanmar amber that’s the subject of ongoing studies. It was a tiny juvenile frog that lived in a tropical forest around 100 million years ago. It’s only the third frog ever found in amber, and is by far the oldest in addition to being the best preserved. Its skull, forelegs, part of its backbone, and the partial hind leg and foot are all preserved, together with a beetle. The problem is, some of the details researchers need to determine what kind of frog it is are missing, like the pelvis. They have just enough information to tantalize them since what they can see indicates that it might be related to some species of toad that live in temperate climates today, but not enough to tell for sure. You know they have to be tearing their hair out in frustration. Hopefully they’ll find another frog with all the bits and pieces they need.

Another surprise from the Myanmar amber is a baby snake only about two inches long, or 5 cm. At first researchers thought it was yet another millipede—I mean, when you’ve found 450 millipedes in amber you probably start to think everything is a millipede—but a scan determined that it was way different. It’s well preserved and even shows some features that modern snakes no longer have, like V-shaped bone spurs on the tail vertebrae that probably helped with stability when snakes first evolved to be limbless. Unfortunately the specimen is missing its skull.

Only one salamander has been found in amber, and it came from a surprising place. The amber was mined from the mountains of the Dominican Republic, which is in the Caribbean near Haiti. But there are no salamanders in the Caribbean today. The salamander in amber dates to around 25 million years ago and proves that salamanders did once live in the Caribbean. Not only that, the amber itself comes from an extinct tree that’s related to a tree native to East Africa. The salamander was a tiny juvenile that fell into a glob of resin after a predator bit one of its legs off. So, you know, it was doomed either way. Poor little salamander.

One really exciting discovery is part of an actual dinosaur tail trapped in amber. It came from a juvenile dinosaur that a scientist found at a market in Myanmar in 2015. The seller thought the tail was a plant, because—you’ll like this—it’s covered in FEATHERS that looked like bits of leaf. It’s dated to 99 million years ago. The feathers were chestnut brown on the tail’s upper surface and white underneath. They’re also very different from modern bird feathers. Researchers aren’t sure which dinosaur species the tail is from, but they do note that the dinosaur died, probably because it couldn’t get free from the resin. It wasn’t like some modern lizards that can drop their tails to escape predators.

Lida Xing, the same researcher who acquired the dinosaur tail in amber also managed to buy a bird in amber in the same Myanmar amber market. Only a few birds have been found in amber and they sell for ridiculous amounts of money—like half a million dollars—to private collectors. As a result, they’re rarely studied. Fortunately, Lida Xing was able to buy the bird in amber and it’s been studied ever since. It’s a young bird that was partially weathered away and squished after it died. It’s about 2 ½ inches long, or 6 cm, and is a type of primitive bird that went extinct at the same time as the non-avian dinosaurs 66 million years ago. It was dark brown and had teeth and clawed fingers on its wings, although both the beak and the finger-wings are missing from the specimen.

Sometimes marine or freshwater organisms are found in amber. For a long time no one understood how this happened, but in 2007 a team of researchers conducted a simple study to find out how it worked. One of the researchers owned some swampy property in central Florida. The team went there and cut pieces out of some pine trees growing in the swamp. Resin flowed from the trees’ injuries, down the trunk, and into the water. The researchers then collected the resin from the water and took it to a lab to examine it. They found water beetles, nematodes, small freshwater crustaceans, mites, even bacteria found in swampy water, all stuck in the blobs of resin. In other words, it’s not a bit unusual for water animals to get caught in resin. The unusual part is when they’re preserved in the resin long enough for the resin to fossilize into amber, and then the really rare part is when they’re found by a human who understands what they’re looking at and realizes it’s important.

Some of the most useful information preserved in amber concerns animal behavior. For instance, the recent discovery of a tick wrapped in spider silk. Spiders don’t usually eat ticks, but occasionally they do, and this tick in amber had been wrapped up in spider silk to immobilize it. Researchers aren’t sure whether the spider planned to eat the tick or was just stopping it from tearing up its web. Either way, it fell out of the web and plopped right into resin, which fossilized and was then found around 100 million years later. From this little piece of amber, we have direct evidence of a spider wrapping up its prey the same way they do today.

Another example is dated to 130 million years ago, when some green lacewing eggs hatched and the larvae and eggs were trapped in resin almost immediately. The green lacewing is a type of flying insect that’s still around today, although the ones found in resin are a species new to science. Since the babies were covered in resin during the act of hatching, researchers have learned a lot about how they emerged from the eggs.

There’s even a piece of amber dated to around 100 million years ago, also found in Myanmar, that shows a dragonfly with a missing head, together with the foot and tail of a tiny lizard. Researchers think the lizard may have caught the dragonfly and decapitated it to kill it, but before it could eat it, both predator and prey were trapped in resin. It’s too bad we don’t have the lizard’s head, because it would be really awesome if it had the dragonfly’s head in its mouth.

Some pieces of amber tell a story like this, like a photograph from millions of years ago. About 50 million years ago near what is now the Baltic Sea, a small mammal, possibly a rodent, bit a mushroom off at its base. A tiny insect, specifically a phasmid, or walking stick, was feeding on the mushroom and jumped away. All this happened just as a blob of resin dropped on the scene. The mammal fled, leaving behind a hair. The insect was trapped but was able to wriggle out of its exoskeleton in an early molt and escape, leaving its exoskeleton behind. The mushroom did nothing, because it was a mushroom. That particular phasmid species is now extinct, as is the mushroom species. Researchers don’t know much about the mammal. They know that the exoskeleton was literally shed moments before it was enveloped in resin because it still shows tiny filaments that would have crumbled away otherwise.

Even more dramatically, another piece of amber, again from Myanmar and about 100 million years old, shows a spider in the act of attacking a wasp. Both the spider, a bristly orb-weaver, and the parasitic wasp are still around today.

Other things are also preserved in amber, from pollen and plant spores to feathers and spiderwebs. It’s mined and gathered in various parts of the world for jewelry, so new amazing specimens could be discovered any day.

I could literally just keep going with this episode for hours talking about what’s been found so far, but I have to stop somewhere so I’ll leave you with one last amber inclusion.

It’s another strange insect new to science, also found in Myanmar amber dated to about 100 million years ago. It was tiny but really weird-looking. Researchers have been referring to it as a unicorn fly because it had a sort of horn sticking up from the top of its head that had three eyes at its tip. Researchers think its specialized horn with eyes on it gave it an advantage when flowers were tiny, as they were back in the early Cretaceous when it lived. Flowering plants had only recently emerged and were diversifying rapidly. It probably ate pollen and nectar. But when flowers evolved to be larger, it lost its evolutionary advantage and went extinct. It also had tiny mandibles that meant it could only eat very small particles of food, long legs, and weirdly shaped antennae.

The unicorn fly was described by our friend George Poinar, who described the weird insect with the triangular head too. And true to form, Dr. Poinar is up to his same tricks. He’s reported as saying that he was “thinking of making some masks based on it for Halloween.”

George, no! The children are frightened! Stop making Halloween masks!

One note about listener suggestions. I’ve been getting a lot of them lately, which is awesome, but I don’t necessarily use the suggestions in order. Which one I pick out for the next episode depends on a lot of things, including how much time I have for research, what strikes me as neat on any given day, and whether I can work a suggestion in to a planned episode about a larger topic. But I promise I do keep all suggestions in a list, and I will eventually get to them all! I’m always delighted to get more, too, so don’t feel like I’m telling you not to send any. Some of the best episodes I’ve done have been from listener suggestions, about animals I’d never heard of before.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

 

Episode 107: Ankylosaurus and Stegosaurus

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This week we’re going to learn about some armored dinosaurs, a suggestion by Damian!

I love that there’s a stock picture of an ankylosaurus:

Stegosaurus displaying its thagomizer:

Thagomizer explained:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week’s episode is another suggestion, this one from Damian, who wants to learn about armored dinosaurs like stegosaurus. It turns out that stegosaurus and its relatives are really interesting, so thanks to Damian for the suggestion!

We’ll start with ankylosaurus, which lived near the end of the Cretaceous period, right before all the non-avian dinosaurs went extinct, about 65 million years ago. A lot of paleontologists pronounce it ANKillosaurus, but it’s properly pronounced anKYlosaurus and for once, I’m finding the correct pronunciation easier, probably because it has the name Kylo right in the middle, like Kylo Ren of Star Wars.

There are a lot of species in the ankylosauridae family, but ankylosaurus was the biggest and is probably the one you would recognize since it’s a popular dinosaur. It’s the one with a big club on the end of its tail, but its leathery skin was studded with armored plates called osteoderms or scutes that made it look something like a modern crocodile. It also had spikes along its sides, although they weren’t as long or as impressive as some of the other ankylosaurids’ spikes.

We don’t know exactly how big ankylosaurus could get because we’re still missing some key bones like the pelvis, but paleontologists estimate it could grow around 33 feet long, or ten meters. Is legs were relatively short and its body wide, something like a turtle. When it felt threatened, it may have just dropped to the ground to protect its unarmored belly and laid there like a huge spiky tank.

Because we only have a few fossil specimens of ankylosaurus, there’s actually a lot we don’t know about it. Much of what we do know is actually mostly from ankylosaurus relatives. Researchers think ankylosaurus actually may not have been a typical ankylosaurid. They aren’t sure if the few fossils found mean it was a rare animal or if it just lived inland, away from water, since fossilization is much more common when water is involved. It lived in what is now North America, although it had relatives that lived throughout much of the world.

Ankylosaurus had a beak something like a turtle’s but it also had teeth that it probably used to strip leaves from stems before swallowing them whole. It probably ate ferns and low-growing shrubs. It had a massive gut where plant material would have been fermented and broken down in what was probably a long digestive process. But some researchers think it may have mostly eaten grubs, worms, and roots that it dug up with its powerful forelegs or its beak, sort of like a rooting hog. Its nostrils are smaller and higher on its nose than in other ankylosaurids, which could be an adaptation to keep dirt out. This might also explain why ankylosaurus appears different from other ankylosaurids, which definitely ate plants.

Ankylosaurus had a remarkably small brain for its size. Paleontologists think it may have used its massive tail club as a defensive weapon, but they don’t know for sure. The tail might just have been for display, or maybe males used their tail clubs to fight during mating season. It probably couldn’t walk very fast and was probably cold-blooded, which allowed it to survive after other dinosaurs went extinct after the big meteor struck. Eventually the plants it ate started going extinct, and since it was a big animal that needed a lot of food, it finally went extinct too. Researchers think bird ancestors survived because they were small and could live by eating plant seeds.

One interesting thing about ankylosaurs of all kinds is how they kept from overheating. Large bodies retain heat better than small bodies, which is why polar bears and mammoths are such chonks. Ankylosaurs were massive animals that lived in warm climates. New research published in late 2018 shows that they kept their brains cool by having extremely convoluted nasal passages with blood vessels alongside them. This helped cool the blood before it reached the brain, keeping it from overheating.

Ankylosaurus was related to stegosaurus. Stegasaurus lived in North America around 150 million years ago, during the Jurassic, but its ancestors were found in many other parts of the world. Like its cousin, stegosaurus had a small brain but grew to enormous size, as much as 30 feet long, or 9 meters. You definitely know what a stegosaurus looks like, since next to T rex it’s probably the most recognizable dinosaur. It had big dermal plates that stood up in rows along its spine and four spikes on the end of its tail, called a thagomizer. I’m not even making that name up, it really is called a thagomizer and the term really is from the Far Side cartoon. Its forelegs were shorter than its hind legs, and researchers think it probably stood with its head down to browse on low-growing vegetation, with its tail sticking up as a warning to any predator foolish enough to get too close.

The thagomizer spikes were probably used for defense. Not only do a lot of the spikes show injuries, we have a fossilized tail vertebra from an Allosaurus with a hole punched right through it. The hole matches the size and shape of a stegosaurus’s tail spike.

Paleontologists aren’t as sure about what the plates were for. They were made of bone covered with a keratin sheath that might have been brightly colored or patterned. There are signs that the plates contained a lot of blood vessels for their size, which suggests they helped with thermoregulation—that is, they might have helped the animal absorb and shed heat. Then again, new studies also suggest that the males had larger, broader plates while females had smaller, sharper ones. This argues that the plates might have been for display. Of course, they could be for both display and for thermoregulation.

Sometimes you’ll hear that stegosaurus had such a small brain that it had a second brain in the hip to help it control its tail. This isn’t the case, though. There is a canal in the stegosaurus’s hip near the spinal cord, but this is something found in other dinosaurs and in modern birds. In birds it’s where a structure called the glycogen body is, but researchers don’t actually know what the glycogen body is for. That’s right, something present in all birds, even chickens and pigeons, is more or less still a mystery to scientists. But whatever it is, it’s not a second brain.

There are other mysteries associated with the stegosaurus, like how it ate. It had a tiny head for its size, about the size of a dog’s head, with peglike teeth that seem to have been used for chewing or shearing plant material. But because the head was so small, and the teeth weren’t shaped for grinding, it probably couldn’t have chewed its food up like modern grazing mammals do. But it also doesn’t seem to have ingested gastroliths, small stones used for grinding up food in the stomach.

There were lots of other armored dinosaurs, generally related to stegosaurus and ankylosaurus. I was going to talk about triceratops too, but technically it didn’t have armor, just head frills and horns. Besides, I think triceratops and its relations need their own episode pretty soon. So we’ll finish up with another ankylosaurid, Akainacephalus.

The only fossil we have of akainacephalus was discovered in 2008 in Utah. It’s a remarkably complete fossil, including the skull and jaws, and has been dated to around 76 million years old. It had a spiky ridge over its eyes and short triangular horns on its cheeks that pointed downward. It also had a tail club that ankylosaurids are known for.

Akainacephalus was formally described in 2018 as not just a new species of ankylosaurid, but one in its own genus. Even though it was found in North America, researchers have determined that it’s more closely related to the ankylosaurids that lived in Asia.

Before Akainacephalus evolved, Asia and North America were connected with a land bridge due to low sea levels. This land bridge is called Beringia, and while it’s currently underwater, at different times in the past it’s been exposed and allowed animals to cross from Asia to North America and from North America to Asia. Beringia is about 600 miles wide, or around 1,000 km, when it’s above water. At the moment, it’s represented by a couple of little islands in the shallow Bering Strait, since it’s been underwater for the last 11,000 years.

Previously researchers thought this land bridge had only been open once during the Cretaceous, but that was before paleontologists examined akainacephalus. Since akainacephalus is related to ankylosaurids that lived in Asia after the land bridge was submerged, it’s possible there was a second opening of Beringia that allowed akainacephalus’s ancestor to migrate from Asia to North America.

That’s one of the really neat things about science. You start by looking at a cool spiky fossil skull, and you end up learning something new about how deep the oceans were 80-some million years ago.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 103: Trace Fossils

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You may know what fossils are (I hope), but have you heard of trace fossils? You have now!

A giant ground sloth footprint with a human footprint inside it, made some 11,000 years ago:

Climactichnites:

A “devil’s corkscrew”:

A Paleocastor fossil found at the bottom of its fossilized burrow:

Stromatolite:

Coprolites:

Gastroliths found with a Psittacosaurus:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re going back in time to look at fossils, but these aren’t regular fossils. They’re called trace fossils, or ichnofossils. Instead of fossilized bones and other body parts, trace fossils are records of where organisms were and what they were doing.

Fossil footprints are one of the most common trace fossils. We have lots of dinosaur footprints, and from them we know that dinosaurs held their tails off the ground, that some dinosaurs traveled in herds with the young in the middle, and things like that. A fossil footprint is formed when an animal steps in soft mud or sand, usually near water, and the resulting footprints were covered with sediment which then dried, protecting the footprints. If the footprints continued to be protected from water and other processes that might wipe them out, over the years more and more sediment was deposited on top, eventually compacting it so that pressure and chemical reactions within the sediment turned it to stone. This is why we sometimes have two impressions of the same footprints: the actual footprints and a cast of the footprints made by the sediment that filled them initially.

The White Sands National Monument in New Mexico has so many footprints of so many animals around what was once a lake that it’s referred to as a megatrack. Seriously, we’re talking hundreds of thousands of footprints. In 2014 a team studying the tracks found a set of ancient human footprints, the first ones found in the park. But while the tracks were well preserved, the team couldn’t pinpoint how old they were. They invited other researchers to come examine the prints to help date them.

In 2016 a British paleontologist named Matthew Bennett came to examine the prints, but while he was there, he took a look at some giant ground sloth prints nearby. And when he did, he made an amazing discovery. There was a sloth footprint with a human footprint on top of it, actually within the sloth’s footprint. The sloth’s print was 20 inches long, or almost 51 cm. And after that, the next sloth footprint also had a human footprint in it. And after that another. And another. And another. Ten sloth footprints in a row had human footprints inside.

Since the tracks were made in sandy lake mud and both tracks were reasonably clear, the researchers determined that the tracks were probably left on the same day. In other words, the human was probably trailing the sloth.

But that’s not all. Bennett and the other scientists at the site followed the tracks of both sloth and human and found marks where the sloth turned around and reared on its hind legs to face the approaching human. And there are more human prints that approach at a different angle—not just human prints, but prints that suggest the human was actually tip-toeing.

The most likely explanation is that the humans were hunting the sloth, with one human getting its attention while a second crept up behind it. But we don’t know for sure. One odd thing is that the human trailing the sloth actually had to stretch to step inside each sloth print. Even small giant ground sloths were enormous, nine or ten feet long, or about three meters, with long curved claws. Ground sloths were plant-eaters that used their claws to strip leaves from branches and dig giant burrows, but the claws made formidable weapons too. It’s possible that the ancient human was just amusing himself by stepping exactly in the sloth’s prints.

Since this initial finding, researchers have found more sites where sloths appear to have turned to face an aggressor, possibly humans. The age determined for the prints, around 11,000 years old, corresponds with the time that giant ground sloths went extinct in North America. Researchers have long suspected that humans hunted them to extinction, and now we may have some direct evidence that this happened.

But fossil footprints aren’t just of big animals. Small squidgy ones leave footprints too, or trails that show where an animal traveled even if it didn’t actually have feet. For instance, 510 million years ago, during the Cambrian period, a creature lived along the shores of a shallow sea and left tracks that have been found in North America. The fossil tracks are called Climactichnites and while we don’t know what animal actually left them, paleontologists have determined that there were two species and that they were probably slug-like in appearance, possibly an early mollusk, since modern slugs and their relatives sometimes leave similar tracks. We even have some body prints of the stationary animal, and some of them were 27 inches long, or 69 cm.

Similarly, fossilized burrows are considered trace fossils. But often fossilized burrows don’t actually look like holes in the ground. Instead, the burrow has filled up with soil that then fossilizes, leaving the shape of the burrow behind in a rock that looks different from the surrounding rock. And these can be remarkably difficult to identify in some cases.

Back in 1891, a rancher in Nebraska showed a visiting geologist some weird formations he’d found. The geologist, Erwin Barbour, didn’t know what they were. He and the rancher dubbed the formations “devil’s corkscrews,” and probably had a laugh. But the formations did look like corkscrews—but they were enormous, taller than a full-grown man and always situated straight up and down. Some were as long as ten feet, or three meters.

Barbour suggested that the corkscrews were freshwater sponges, since the prevailing belief was that the area had once been a lake. Other scientists thought they might be the remains of fossilized tree or other plant roots. And a couple of people thought they might be fossilized burrows of an unknown rodent.

Those people were right, of course, but at the time, no one knew for sure. And if the corkscrews were burrows, what made them?

The mystery was solved when fossils of a beaver relative called Paleocastor was found at the bottom of one of the corkscrews. Unlike modern beavers, it wasn’t an aquatic rodent but a burrowing one, and it lived around 25 million years ago. Once the Paleocastor fossil was discovered, it was clear that the marks noted on some of the corkscrews, which had been interpreted as scratch marks from claws, were actually tooth marks. They perfectly matched Paleocastor’s teeth, which meant the beaver excavated its corkscrew-shaped burrow by chewing through the dirt instead of digging through it.

So why did Paleocastor dig burrows with such an odd shape? The answer may lie in another fossil found not in the bottom of the burrow but stuck in the corkscrews. Zodiolestes was an extinct weasel relative. Possibly it had gone down the burrow while hunting beavers, become stuck in the tight corkscrew turns in the tunnels, and died.

More recent research shows that Paleocastor burrows were frequently connected to one another with side passages, sometimes hundreds of burrows joined together like the burrows and tunnels of modern prairie dogs. This suggests that Paleocastor was a sociable animal that lived in colonies.

As it happened, Dr. Barbour had been right about one thing. The area where the devil’s corkscrews were initially found had once been a lake. His mistake was not realizing that the structures had been dug into the ground where the lake had once been.

Some of the oldest fossils known are trace fossils called stromatolites. These are stones that were formed by microbes. Early life consisted of microbial mats, colonies of microorganisms like bacteria that grow on surfaces that are either submerged or just tend to stay damp. Microbial mats are still around today, often growing in extreme environments like hot springs and hypersaline lakes. When microbial mats grow on a sea or lake floor, they tend to build upwards, forming columns or even reefs that rise out of the mud and toward the light. But while stromatolites are formed by bacteria, they’re not formed of bacteria. Instead, the stones are formed from grains of sand and other sediments that were trapped and cemented together within the mats, which forms a thin layer of limestone. The layers grow over time, giving stromatolites a banded or striped pattern. But it can be really hard to tell them apart from regular old non-stromatolite rocks that also happen to have a banded pattern. Geologists spend a lot of time studying stromatolites and suspected stromatolites to find out more about them. Microbial mats evolved almost 3.5 billion years ago and it’s possible they were around as much as 4 billion years ago. The earth is about 4.5 billion years old, if you were wondering.

But let’s return to more modern times, with animals and fish and things. Another trace fossil is one I’ve mentioned here a few times, the coprolite. A coprolite is a fossilized poop. Most of the original organic material has been mineralized, preserving it. Coprolites are valuable since paleontologists can cut them open to find out what the animal was eating, if it had intestinal parasites, and lots of other information. Coprolites are also frankly hilarious. Did you know that if you become a scientist whose area of study is coprolites, you’re called a paleoscatologist?

We’ve also talked about gastroliths before. Gastroliths are small stones swallowed by an animal to help digest its food. The stones especially help grind up plant material, which eventually causes the stones to become smooth. Lots of animals use gastroliths for digestion, including birds that eat plants, crocodiles and alligators, seals and sea lions, although they may swallow them by accident, and many dinosaurs, especially sauropods. We know sauropods swallowed stones to help in digestion, because we’ve found gastroliths associated with sauropod fossils.

Other trace fossils include marks an animal may have made during its life, like those tooth marks preserved in the devil’s corkscrews. Skin imprints, or fur or feather imprints, are also trace fossils but are incredibly rare. Sometimes a skin imprint remains in place around an animal’s fossilized body parts, which gives paleontologists incredible insight into what an animal looked like while it was alive. That’s how we know a lot of dinosaurs had feathers. Root cavities are trace fossils too, caused not by animals but by plant roots that burrow into the soil but rot away, leaving a hole that fills with dirt and later fossilizes in the shape of the original roots. There’s even a type of trace fossil called a urolite, which was caused when an animal urinated and the urine stream left marks on soft ground.

Since trace fossils are usually hard to match up with the animal that made them, trace fossils are given scientific names of their own. This allows scientists to refer to them without guessing at what made them, and it reduces confusion.

Trace fossils are remains of biological activity. But animals and plants aren’t the only things that can move soft soil. Cracks in dried-out mud are sometimes fossilized, as are ripple marks from water and little dimples made by raindrops or bubbles. Geologists use these fossilized moments in time to help determine how the rock strata have been shifted by geologic forces. They know that a rock that shows ripple marks was once flat, so if it’s been tipped up sideways or deformed into a curve, they can determine what forces were at work on the rocks over the centuries.

It’s not all that uncommon to find these non-biological traces alongside trace fossils and body fossils. I’ve seen big flat rocks that show the bottom of a shallow sea, with ripple marks, the tracks of tiny animals that trundled around looking for food in the sandy mud, and the occasional fossil like a bryozoan or fragment of shell. It’s the closest thing we have to photographs of prehistoric times.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 098: River Dolphins

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This week let’s learn about some unusual cetaceans, river dolphins!

An Amazon river dolphin and the nose of another Amazon river dolphin:

Another Amazon river dolphin. Note the teeny eye and disk-like teeth:

A South Asian river dolphin. Note the almost nonexistent eye:

A Chinese river dolphin in better days:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re going to learn about an animal I’ve wanted to cover for a long time but never got around to, the river dolphin.

All whales and almost all dolphins live in the ocean. They can survive for a short while in fresh water but need saltwater to thrive. But as the name suggests, the river dolphin lives in rivers, usually in fresh water and sometimes in the brackish water where rivers empty into oceans. Brackish just means a mixture of fresh and salt water, so it’s saltier than fresh water but not as salty as ocean water. When I was a kid I thought it meant ocean water with a lot of seeweed and dead leaves in it, because I thought the word brackish had something to do with bracken, which is a type of fern.

There are only a few species of river dolphin alive today. They live in warm water and have very little blubber as a result. They primarily use echolocation to navigate since river water tends to be muddy and hard to see through. Their flippers are broad and most have long snouts and flexible necks, or at least flexible compared to other cetaceans. All river dolphins are endangered due to pollution, habitat loss, and accidental drowning in fish nets, with the Chinese river dolphin only having been declared extinct in 2006.

River dolphins evolved from dolphins that once lived in the ocean, but most aren’t closely related to the marine dolphins alive today. Researchers think that when modern dolphins and other toothed whales evolved, they outcompeted their more primitive cousins, who moved into freshwater habitats as a result.

A few years ago, fossils of an extinct river dolphin that grew more than nine feet long, or almost three meters, were found in Panama. It lived around 6 million years ago in the Amazon River, but researchers don’t think modern river dolphins are closely related to it. In other words, freshwater dolphins have evolved repeatedly in different parts of the world to fit an available ecological niche.

In the case of the newly discovered fossil river dolphin, Isthminia panamensis, it probably lived in the warm, shallow Caribbean Sea between North and South America before the Isthmus of Panama formed. It took millions of years for the isthmus to form, with undersea volcanos first emerging from the ocean around 15 million years ago to form islands, then the land itself being pushed upward as the Pacific Plate slid underneath the Caribbean Plate. Researchers think the isthmus became fully formed around 3 million years ago, separating the Atlantic Ocean from the Pacific and connecting North and South America. Because we have Isthminia panamensis’s fossil from the Amazon River, we can hypothesize that by around 6 million years ago, there wasn’t enough of the original Caribbean Sea habitat to support the dolphins and they had already moved into the Amazon River and adapted to life in freshwater.

The river dolphin isn’t the only cetacean that lives in freshwater. There’s a species of porpoise called the finless porpoise that lives around Asia in shallow coastal waters, but often spends at least part of the time in mangrove swamps and in rivers not too far from the sea. Porpoises and dolphins look very similar but belong to different families, which means they aren’t actually very closely related at all. Like, seriously not related at all. Like, the difference between horses and cows. The finless porpoise can grow almost seven and a half feet long, or over two meters, and is called finless because it doesn’t have a dorsal fin. Instead, it has a dorsal ridge lined with tubercles, or bumps, that contain nerve endings. Researchers don’t know what purpose the tubercles serve. Porpoises use echolocation but their clicks are much higher in frequency than dolphins’, so high that humans can’t hear most of them.

There are three families of river dolphins still living today, Platanistidae, Iniidae, and Pontoporiidae.

Platanistidae are the Indian dolphins, with only one species alive today. The South Asian river dolphin lives in South Asia. There are two subspecies, the Ganges River dolphin and the Indus River dolphin. Young South Asian river dolphins have sharp, thin teeth, but as the dolphin matures, its teeth become flatter and squarish, almost like disks. It eats fish, crustaceans like shrimp, and some dolphins may also eat water birds and even turtles. Its rostrum, the word for a cetacean’s beak, is considerably longer in females than in males, sometimes like 8 inches longer, or about 20 cm.

The South Asian river dolphin is sometimes called the blind dolphin because its eyes are basically only useful for sensing light. They don’t even have lenses. It has a very small dorsal fin, not much more than a bump, a powerful tail, and is brown in color, and grows up to ten feet long, or almost 3 meters. It uses echolocation to navigate in the murky river water and find prey. It also usually swims on its side, which also gives it the name side-swimming dolphin. It does this so it can trail the tip of a flipper along the river bottom to feel for shrimp and mollusks.

It’s such an unusual dolphin, even for river dolphins, that researchers are studying fossil dolphins to figure out how the South Asian river dolphin evolved. Two years ago, a fossilized dolphin skull found in 1951 in Alaska and held in the Smithsonian’s collection ever since was evaluated and determined to be a distant relative of the South Asian river dolphin. It lived about 25 million years ago, around the time that ancient whales were evolving into the two groups we have today, toothed whales, which includes dolphins, and baleen whales.

The South Asian river dolphin has been evolving separately from marine dolphins for at least the 25 million years since its relative was swimming around in the Arctic Ocean. Research on its echolocation suggests that the Ganges River subspecies of the South Asian river dolphin probably has biosonar that more closely resembles that of ancient toothed whales than modern toothed whale and dolphin echolocation does. It has a much deeper voice than marine dolphins of about the same size have.

I tried very hard to find a recording of a Ganges River dolphin, or any South Asian river dolphin, but all I found was this, the echolocation of an Amazon river dolphin:

[river dolphin sound]

The Amazon river dolphin is a member of the Iniidae family of river dolphins. It’s the biggest of the river dolphins, and adults are often pink in color. In all other river dolphins, and most cetaceans in general, females are larger than males, but male Amazon river dolphins are larger than females. Babies are dark gray, fading to lighter gray as they grow up. Adults can appear pink because the skin is often pale and in warm water, the blood shows through the skin. The Amazon river dolphin has small eyes, but it sees a lot better than the South Asian river dolphin.

Most river dolphin species aren’t nearly as sociable as marine dolphins and are usually only found singly or in groups of two or three. Male Amazon river dolphins often fight each other when females are around. If a male Amazon river dolphin meets some females, he will pick up a branch or stone and carry it around to impress them.

Amazon river dolphins eat fish, including piranhas, freshwater crabs, turtles, and other small animals. Sometimes a dolphin will participate in cooperative hunting with giant otters and the tucuxi, another species of dolphin that lives in the Amazon basin. The three species eat different types of fish so they all benefit from hunting together.

The tucuxi isn’t actually a river dolphin although at least some individuals live in rivers. It’s considered a marine dolphin, and you can tell the difference just by looking at it. It looks like a small bottlenose dolphin, about five feet long, or 1.5 meters, and unlike river dolphins its rostrum is relatively short.

The third family of river dolphin is Pontoporiidae, and there’s only one species alive today. Just to show that nature isn’t cut and dried, the La Plata dolphin doesn’t always live in fresh water. It lives around the coast of southeastern South America and while some do spend their whole lives in rivers, most La Plata dolphins live in the ocean.

Finally, let’s talk about the Chinese river dolphin, the one that’s recently extinct, also called the baiji. Technically it’s functionally extinct because although there may be one or two still alive, there aren’t enough to continue the species into another generation. River dolphins do very poorly in captivity, usually dying within months, so even if conservationists had billions of dollars and the cooperation of every single person on earth to save the Chinese river dolphin, there’s nothing they could do at this point. In fact, in 2006 a research team searched for the dolphin for six weeks to put a conservation action plan into place for it, but they didn’t find any. That’s when it was declared extinct.

The Chinese river dolphin lived in the Yangtze River and grew up to 8 feet long, or 2.4 meters. It was blue-gray with a paler belly, and like many other river dolphins, its rostrum was slightly upturned. It also had poor vision. It was once common along much of the Yangtze, some 1,100 miles of river, or 1,700 km, but massive increases in pollution of the river, collisions with boats caused by the noise of boats overwhelming the dolphins’ echolocation, poaching, entanglement in fishing nets, loss of habitat due to damming of the river, and overfishing drove it to extinction within about five decades. The last confirmed sighting of a Chinese river dolphin was in 2002, with an unconfirmed sighting in 2007.

This is a depressing way to end the episode, so let’s finish up with a long-ago relative of the South Asian river dolphin. Zarhachis flagellator lived during the Miocene, about 16 million years ago, and had a really long rostrum. Like, super super long. Its skull was about four feet long, or 1.2 meters, which makes it sound like it must have been a really big dolphin, but it wasn’t. Its actual braincase was less than a foot long, maybe 8 inches or so, or 20 cm. The rest of the length was rostrum. In other words, it had a head about the size of your head, and a long thin beak full of sharp teeth that was something like three feet long, or almost a meter. Tonight when you brush your teeth, think about that. Think about how hard it would be to reach all your teeth if you had a mouth that stuck out three feet from your head. You’d need a really long toothbrush.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 092: Marine Reptiles

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This week we return to the sea to learn about some marine reptiles, both living and extinct!

A marine iguana, eatin:

Another marine iguana, swimmin:

Maybe Darwin was right about the marine iguana looking like imps of darkness:

A mosasaurus skeleton:

A plesiosaur skeleton:

Thalattosaurs:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

It’s been a while since we had an episode about the ocean, and I thought it would be interesting to learn about reptiles that evolved to live in a marine environment. Some marine reptiles we’ve already covered in previous episodes, including saltwater crocodiles, sea turtles, and sea snakes. But we haven’t talked much about extinct marine reptiles, and I don’t think we’ve ever had an episode about the marine iguana.

The marine iguana is only found on the Galapagos Islands. It eats seaweed and algae that grow in shallow water around the islands, so it swims and dives to find its food. It’s a large, strong iguana that can grow up to five feet long, or 1.5 meters, with short legs, a short snout, and a row of spines along its back. It’s black or gray in color, which absorbs heat from the sun and keeps the iguana warmer. Many have colorful markings, especially males during the breeding season. The markings might be red or pink, blue-green, yellow, or off-white, depending on subspecies. Some researchers think the kinds of algae eaten by the various subspecies of marine iguana also contributes to the colors of their markings. Males are larger than females.

The marine iguana is well adapted to swimming, although it’s not a fast swimmer. It uses its flattened tail and partially webbed toes to propel itself through the water, and the spines on its back keep it stable in the water. It has long claws that it uses to hold onto rocks to keep from being swept away. Newly hatched babies can swim immediately, but they stay out of the water whenever possible until they’re at least a year or two old. The water around the islands is cold, so the marine iguana will forage in the water for a short time, then come back on land to bask in the sun and warm up.

Only the biggest marine iguanas, mostly adult males, will dive for their food. Females and smaller males usually stay in shallow water, especially at low tide when the algae is easier to reach. A marine iguana can dive up to almost 100 feet, or 30 meters, and stay underwater for half an hour. During bad weather, the iguanas stay on shore, often gathered together to conserve body heat.

Researchers used to think the marine iguana evolved from land iguanas that were swept from Central or South America by storms and floated to the Galapagos islands on rafts of vegetation. Then genetic studies showed that the marine iguana started evolving separately from land iguanas around 8 to 10 million years ago. The Galapagos islands are of varying ages, formed by volcanic activity, but the oldest is only about 3.2 million years old. So obviously the two groups of iguana were separated long before the Galapagos formed. Researchers then speculated that there may have been other, older islands in the Galapagos or nearby that are now submerged, which were where the marine iguanas first started to evolve separately from land iguanas. Then new genetic studies indicated that marine and land iguanas actually separated about 4.5 million years ago, which is not that much of a difference from the oldest islands of the Galapagos, so researchers are back to the original hypothesis. As I’ve said before, science isn’t wrong or right, scientists learn new things and adapt their theories to account for the new information.

For instance, at the moment researchers aren’t sure how marine iguanas shrink during years when weather conditions keep them from finding as much food as they need. I don’t mean they lose weight, I mean they actually shrink. Results of a study published in the journal Nature say marine iguanas shrank up to 2.7 inches, or 6.8 cm, during years with El Nino weather patterns, which brings stormy weather. The iguanas’ bones actually shrunk, making them both shorter and smaller. Not only that, after weather patterns returned to normal and the iguanas were able to find more and better food, the shrinking reversed and they grew larger again. Shrinking reduces the iguanas’ dietary requirements, making them able to survive on less food without long-term health issues.

Because the marine iguana eats algae and other plants that grow in the ocean, it ingests a lot of salt. It has a special gland on the nose that filters excess salt from the blood, which the iguana then expels by sneezing. Many times marine iguanas look like they have white markings on the head, but in actuality it’s just dried salt that they’ve sneezed out.

Like most of the animals that live on the Galapagos Islands, the marine iguana is found nowhere else in the world. It would have been easy for early visitors to the islands to have eaten them to extinction the way they did so many other species. But sailors considered marine iguanas so ugly that they refused to eat them. Even Charles Darwin called them disgusting imps of darkness. That’s harsh, especially since I think they’re cute, but it kept them safe until people understood the need for conservation.

Many marine reptiles are extinct, including the ichthyosaurs we talked about in episode 63. These days the top predators in the ocean are sharks and whales, but mosasaurs and plesiosaurs used to fill those ecological niches.

Mosasaurs looked a lot like sharks in some ways, and like whales in other ways, but they were reptiles. There were a lot of them, from one barely more than three feet long, or 1 meter, up to some species that grew some 50 feet long or more, or up to 17 meters.

All species of mosasaur had four flippers, long powerful tails, and small heads with short necks. Its skull resembled a snake’s in that it was flexible, allowing the mosasaur to swallow prey larger than its head. It also had double-hinged jaws that could open extremely wide. It’s also possible that the mosasaur had a forked tongue. We have skin impressions of mosasaurs, so we know at least some species had finely scaled skins like snakes. Some species had fluked tails shaped like a shark’s tail. The mosasaur used its tail to propel itself through the water, with its flippers only helping it maneuver. Some researchers think the closest living relative of the mosasaur is the Komodo dragon and other monitor lizards, but others think the mosasaur was more closely related to snakes.

The mosasaur came to the surface to breathe every so often like other marine reptiles. It also gave birth to live young. It probably swallowed its prey whole, although some species had specialized teeth that allowed them to crush mollusk shells, such as ammonites. Some studies suggest the mosasaur may even have been warm-blooded. It went extinct at the same time as the dinosaurs.

The plesiosaur looks similar to the mosasaur in many ways, including overall shape and size, but was probably more closely related to turtles than to the mosasaur. Most plesiosaurs had a broad body, a very long neck and small head, and a fairly short tail. It propelled itself with its four long flippers like sea turtles do and was probably relatively slow. Some plesiosaurs, known as pliosaurs, had shorter necks and much larger heads, and swam much faster.

Like the mosasaur, the plesiosaur may have been warm-blooded, and gave birth to live babies instead of laying eggs. The longest plesiosaur was called elasmosaur, which had an extremely long neck. Some elasmosaur species had as many as 76 neck vertebrae. This is your reminder that almost all mammals have seven neck vertebrae. While the elasmosaur could grow up to 50 feet long, or 15 meters, much of its length was neck. Researchers used to think plesiosaur necks were flexible like a goose or swan’s neck, but new findings indicate that it was probably fairly stiff and could mostly just move side to side. Skin impressions show slightly wrinkled skin and some species may have had a tail fluke.

Long-necked plesiosaurs had large eyes and probably hunted by sight. Researchers hypothesize that the long neck might have allowed it to sneak up on fish before they could sense the movement of water from the plesiosaur’s approaching body.

At least one elasmosaur was a filter feeder, with interlocking teeth that it used to filter small prey from either the water or sand, or possibly both. It shows many similarities in skull shape to early baleen whales, too. Researchers think it had a valve at the base of the nostrils that closed them while the animal was feeding, since plesiosaurs and some other marine reptiles have nostrils that open into the mouth.

Like mosasaurs, plesiosaurs died out at the same time as the dinosaurs. They did not live on as the Loch Ness Monster, okay?

While mosasaurs and plesiosaurs lived throughout the world’s oceans, the various species of thalattosaur lived around what is now North America, western Europe, and parts of China. They lived during the mid-Triassic period, up to about 250 million years ago, and we don’t know a whole lot about them because we don’t have all that many fossils. We’re not even really sure where they fit in the reptile family tree.

The thalattosaur hunted in warm, shallow water but otherwise probably lived on land. It resembled a lizard, but with some interesting adaptations to the water. It had four short legs, probably had webbed toes, its body was slender and flexible, and its long tail widened at the end to form a paddle. Some species grew up to 13 feet long, or 4 meters. Some species had nostrils near the eyes, some had snouts that point downward, some had snouts that point upward. Some probably ate jellyfish and other soft foods, others probably ate fish, and a few had teeth that could crush mollusk shells—and had teeth on the roof of its mouth.

This actually isn’t unusual in reptiles and some amphibians. Most snakes have a double row of teeth in the upper jaw, one row growing from the jaw like normal, the other row growing from the roof of the mouth. Some lizards have small teeth that grow from the roof of the mouth, as do many frogs. These help the animal grasp its prey and keep it from escaping while it’s being swallowed whole. This is pretty neat, but it’s not as neat as shrinking iguanas. Nothing beats that.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 086: Ammonoids and Nautiloids

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Is it extinct? Is it alive? What is the difference between the ammonite and the nautilus? Did Kate get the two confused her whole life until a few months ago and thought they were both extinct? Maybe.

A fossilized ammonite shell:

Another fossilized ammonite shell of a different shape:

A third fossilized ammonite shell of a yet different shape:

A gigantic fossilized ammonite shell:

A fossilized ammonite shell of gem quality, called an ammolite:

This is what an ammonite might have looked like when it was alive. I drew this myself IN MS PAINT because I couldn’t find anything online I liked. There’s 15 minutes of my life I won’t get back:

This is an alive and not extinct nautilus:

Another alive and not extinct nautilus:

The slimy or crusty nautilus. Look, I don’t make these names up:

A nautilus tucked up in its shell and peeking out to see if that diver is going to eat it:

You can contribute to helping conserve the nautilus:

Save the Nautilus

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week let’s learn about two groups of mollusks, ammonoids and nautiloids. One group is extinct, one is still around…but they both look a lot alike, and they’re way more interesting than the word mollusk makes them sound!

We’ll start with ammonoids, specifically ammonites. Ammonites first appear in the fossil record around 409 million years ago, but they died out at the same time as the dinosaurs, around 66 million years ago. Many ammonite fossils look like snail shells, but the shell contains sections inside called chambers. The largest chamber, at the end of the shell, was for the ammonite’s body, except for a thin tube that extended through the smaller inner chambers, which allowed the animal to pump water or air into and out of the chambers in order to make itself more or less buoyant in the water. Some ammonites lived at the bottom of the ocean in shallow water, but many swam or floated throughout the ocean.

Comparing ammonites to snail shells may not give you the right idea about ammonites, though. Even big snails are pretty small. While many ammonites were no larger than modern snails, many others were bigger than your hand, sometimes twice the size of your hand even if you have really big hands. But during the Jurassic and part of the Cretaceous, some ammonites got even bigger. One species grew almost two feet across, or 53 cm, another grew some 4 ½ feet across, or 137 cm, and one species grew as much as 6 ½ feet across, or 2 meters. It was found in Germany in 1895 and dates to about 78 million years ago. And it wasn’t actually a complete fossil. Researchers estimate that in life it would have been something like eight and a half feet across, or 2.55 meters.

We have a lot of ammonite fossils, and many of them are beautifully preserved. Some still show a mother-of-pearl layer, a lustrous, iridescent layer of shell that modern molluscs still form. Some ammonite fossils are so lustrous that they’re considered gems, called ammolites. Ammolites are usually polished and made into jewelry. In the olden days people thought ammonites were petrified snakes, and would sometimes even carve the end of the ammonite shell into a snake’s head.

Many fossil ammonites aren’t fossils of the actual shell. When an ammonite died, its empty shell would fill with sediment. Frequently the shell itself wasn’t preserved, but the sediment inside was. That gives us elaborate casts of the insides of ammonite shells, in such good condition that researchers can determine the internal anatomy of the shell. We know mosasaurs frequently ate ammonites because we have fossils with tooth marks that match mosasaur teeth.

There are so many ammonite fossils that paleontologists can date layers of rock by examining which species of ammonite appear in it, called index fossils. Different species frequently had much different shells, some smooth, some with spines or ridges, with tight coils or open coils. Some didn’t coil at all, and instead were straight or had only one or two bends.

But despite all these thousands upon thousands of ammonite fossils, we still don’t know what the animal’s soft parts looked like. Hardly any impressions of ammonite bodies are preserved, only the shells. But ammonites are related to cephalopods like squid, so researchers believe they probably had tentacles.

Nautiloids are also cephalopods. They’re related to ammonites but not closely, about as closely as they’re related to squid. And nautiloids are still alive.

I only found that out recently. A few months ago I came across a picture of a man holding a big snail-like shell with eyes and a bunch of small tentacle things sticking out of the end. I thought it was photoshopped, because I knew those things were extinct! Then I realized that I’ve had nautilus and ammonite mixed up my whole life, and thought they were both extinct and basically the same animal.

They do look a lot alike. Nautilus shells are smooth and rounded like a snail shell, and like the ammonite, nautilus shells also contain chambers filled with gas that keeps the animal from sinking. The nautilus’s body is in the last chamber and extends outside of the shell, with a pair of simple eyes, a beak-like mouth, and as many as 90 small tentacles around the mouth. The top of the shell is striped with brown, while the bottom is white.

Nautilus tentacles are retractable and don’t have suckers the way other cephalopod tentacles do. They do have ridges and secrete sticky mucus that helps them keep hold of their prey. The nautilus also has tentacles around its eyes that are different from its mouth tentacles, and researchers think they act as sensory organs, detecting scent trails in the water. When a nautilus wants to rest, it holds onto a rock with its mouth tentacles so it won’t drift away.

Like squid, the nautilus has a tongue-like structure called a radula, which is studded with exactly nine teeth that it uses to cut up pieces of its prey, mostly crustaceans. It also eats carrion. Like other cephalopods, the nautilus has blue blood instead of red since it contains hemocyanin instead of hemoglobin. Also like squid and other cephalopods, the nautilus has a siphon, properly called a hyponome. In the nautilus, the hyponome is a flap that’s folded over to form a tube, instead of an actual tube in squid and octopus. The animal sucks in and expels water through the hyponome, which propels it through the ocean. If it’s threatened, the nautilus can actually withdraw all the way into its shell like a snail, covering the entrance with two large, folded tentacles.

The first fossil nautiloids are found in rocks dating to the Cambrian period, some 500 million years ago. Earlier nautiloids are sometimes straight, sometimes slightly curved, and sometimes coiled like ammonite shells. Even so, overall the nautilus hasn’t changed much since the Cambrian. Like the ammonite, some species of nautiloid once reached over 8 feet across, or 2.5 meters.

Today there are only six species of nautilus left, and they’re endangered due to habitat loss, pollution, and poaching. The shells of larger individuals can be worth a few hundred dollars to collectors, and while selling the shells is illegal in many countries, as long as there are unscrupulous or just clueless people who buy the shells, poaching of nautiloids will continue to be a problem. A good rule is that if you’re a tourist and someone is selling any kind of animal part, don’t buy it. Even if you think it’s harmless, you might be contributing to the extinction of an animal—plus, it’s probably going to get confiscated by customs anyway.

The problem is that the nautilus matures very slowly. It lives to be over 20 years old, but it isn’t mature until it’s about 15 years old. Its eggs take a long time to hatch too. So the nautilus is slow to recover from overhunting, which makes it vulnerable to extinction.

One species of nautilus is so rare it’s only been seen a few times, and hadn’t been seen in more than 30 years until one was spotted in 2015 off the coast of Papua New Guinea. It’s called Allonautilus scrobiculatus, and unlike other nautilus species, its shell is covered with a thick coating of hairy slime that gives it its popular name, the slimy nautilus or crusty nautilus. It grows to about 8 inches across, or 20 cm. Its close relative Allonautilus perforates is even rarer. In fact, it’s never been seen alive, and researchers don’t know much about it since all they have to study are empty shells found drifting in the water. It grows to about 7 inches across, or 18 cm.

Most living nautiloids are about that size, but the biggest is a subspecies of the chambered nautilus, often called the emperor nautilus. Before you get too excited, though, the biggest ones only grow to about ten inches across, or 25 cm.

Nautiloids don’t like water that’s too warm so they usually live near the bottom of the ocean, although their shells can’t withstand the pressures of abyssal depths. If a nautilus descends too far, its shell implodes and it dies instantly, like a hapless diver in a malfunctioning bathysphere. Nautiloids live in the Indo-Pacific Ocean and like the deeper parts of coral reefs.

So why did ammonites die out during the Cretaceous-Paleogene extinction event while nautiloids didn’t? Researchers think ammonites laid eggs that floated near the top of the ocean, while nautiloids lay eggs that stay on the bottom of the ocean. Specifically, female nautiloids attach their eggs to rocks in warm water, which take up to a year to hatch. Eggs at the bottom of the ocean were protected from most of the effects of the meteor impact, while those near the surface were killed.

Is it possible that some ammonites survived and still live in the deep sea, unknown to humans? I’m going to say probably not. Ammonites shared a lot of physical similarities with nautiloids, so they probably weren’t able to live in the deep sea without imploding. While it would be amazing if scientists discovered a living ammonite, we should celebrate that the humble nautilus is definitely still alive. It’s still blowing my mind, to be honest.

If you’d like to help nautilus conservation efforts, you can visit save the nautilus.com for more information. I’ll put a link in the show notes.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 085: Crocs, Gators, and Their Massive Terrifying Cousins

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This week’s episode is all about crocodiles, alligators, and their relations. Thanks to Damian, John Paul, and John Paul’s son for the recommendation!

A Chinese alligator:

It’s easy to tell alligators and crocodiles apart. Just ask them to stand side by side, then lean over and look down to see the head shape. Broad-headed alligator on left, slender-headed crocodile on right:

Saltwater crocodile. Look, I’m only going to say this once: DO NOT SIT ON A CROCODILE OKAY THAT IS JUST DUMB AND YOU WILL GET EATEN ONE DAY IF YOU KEEP ON DOING IT

A gavial:

Black caiman:

Further reading:

A newly discovered difference between alligators and crocodiles

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week’s episode is about crocodiles and alligators, and their relations. Thanks to a couple of different listeners for the suggestion, Damian and John Paul, and John Paul’s son. We’ve touched on crocodiles before in a couple of different episodes, including episode 53 about dragons, but alligators have barely had a mention.

Crocs and gators aren’t actually that closely related, but both are members of the order Crocodilia. This order also includes caimans and gavials, as well as some verrry interesting extinct members.

Crocodilians are amphibious reptiles. They spend much of their time in the water but also spend time on land. They breathe air, lay eggs, and depend on air or water temperature to regulate their body temperature. All crocodilians have evolved to take advantage of their watery habitat: long tails that are flattened laterally, eyes and nostrils close to the top of the head, short legs with webbed toes, and a flap at the back of the mouth that keeps water from flowing into the throat and airways. They can stay underwater for at least 15 minutes without needing to surface for air, and some individuals can stay underwater for close to two hours under the right conditions.

Crocodilians have thick protective scales on much of the body, called scutes, strengthened by osteoderms, or bony plates. Some scutes contain sensory receptors that sense touch, heat and cold, chemical stimuli, and especially the movement of water. Crocodilians see well even in darkness and have good hearing and smell too.

Some mother crocodilians lay her eggs in holes in the sand, but most build a nest out of vegetation. As the vegetation rots, it generates heat that warms the eggs. If the temperature in the nest is constantly above 90 degrees Fahrenheit, or 32 Celsius, more babies develop into males. If the temperature is cooler than that overall, more babies develop into females.

The mother protects the nest, which is usually near her den. Sometimes several females nest close to each other to help each other protect the nests. When her babies start hatching, the mother crocodilian digs them out of the nest since they aren’t strong enough to do it themselves, and carries the babies to water where they are safer. She also protects them for a while after they hatch. This is important, because baby crocodilians are vulnerable to predators—including adults of their own species.

Different species of crocodilians communicate in different ways. Some roar or bellow, some hiss, grunt, slap the jaws shut loudly, splash the head or tail in the water, or blow bubbles. Males often growl infrasonically—a sound humans feel more than hear, and which can cause the water around the male to shiver. That’s creepy. Baby crocodilians still in the egg will mimic tapping sounds, and yelp or grunt to let their mother know when they’re hatching.

One interesting thing about crocodilians is the way they walk. Most of the time a crocodilian walks with its belly touching the ground and its tail dragging. This is called the low walk. But unlike most other reptiles, most crocodilian species have ankle joints that allow it to raise its body up off the ground and walk like a mammal, with only the end of the tail dragging. This is called the high walk. Some smaller species can even run, a bounding gait something like a rabbit’s. Crocodilians can also jump.

If you’ve ever heard the phrase “crocodile tears,” which refers to someone who pretends to feel bad while doing something mean, it comes from the belief that crocodiles wept while eating their prey. The belief goes back at least 900 years and probably longer, and it’s actually based on a real phenomenon. When a crocodilian is in the water, its eyes are protected by both a see-through third eyelid, properly called a nictitating membrane, and by a tear-like lubricant that washes any grit out of the eye. The lubricant is visible when the animal is out of the water, and it looks like the crocodile is crying.

Many crocodilians are ambush hunters. They lie mostly submerged, only their eyes and nostrils above the surface of the water, and wait for an animal to approach. Then they grab the animal with their powerful jaws and drag it into the water to drown. This requires massive bite strength, and crocodilians have the strongest bite of any animal alive. Recently, 3D modeling of an alligator’s head revealed a second jaw joint that stabilizes the jaw and helps distribute the bite force throughout the skull.

In case you were wondering how to tell a crocodile from an alligator, crocodile snouts are more slender than alligator snouts. It’s easy to tell the two apart when their mouths are closed, since only the upper teeth are visible when an alligator closes its mouth, while a crocodile shows both upper and lower teeth.

Besides, there are only two species of alligator alive today, the American alligator that lives in the southern United States, and the Chinese alligator, which lives in eastern China. The Chinese alligator is the smaller species, no more than 7 feet long, or 2.1 meters. While most crocodilians have soft bellies, the Chinese alligator has an armored belly. It lives in marshes, lakes, and rivers but these days it’s critically endangered and mostly restricted to the Anhui Chinese Alligator Nature Reserve. In 1999, conservationists estimated that there were only about 150 Chinese gators alive in the wild. Fortunately, since then more protected habitats have been developed for the gators and captive breeding programs have released many young gators into the wild. Their numbers in the wild are increasing slowly, but since the gators also do well in captivity, it’s estimated that as many as 10,000 individuals live in zoos around the world.

As for the American alligator, back in 1967 it was listed as endangered, mostly due to hunting and the sale of baby alligators as pets. Alligators do not make good pets, which you could probably figure out just by thinking about how big gators get. That would be more than 15 feet long for a big male, or 4.6 meters. Fortunately, conservation made a huge difference to the American alligator and it’s now considered fully recovered from its low point in the 1960s.

The American alligator lives in wetlands throughout the deep southern states, including parts of Texas, across to Florida and up through parts of North Carolina. It eats pretty much anything it can catch, including fish, crabs and other crustaceans, birds, mammals, frogs and other amphibians, and reptiles like turtles and snakes. It also sometimes eats fruit. Because the alligator can tolerate a certain amount of salt water, and frequently lives near the ocean, occasionally one will eat a shark. But sharks sometimes eat alligators too. Alligators also help control the spread of exotic species released in the Florida Everglades and other areas, including Burmese pythons. Full-grown alligators frequently hunt on land, but young alligators mostly stay in the water. Young American alligators have thin yellowish stripes that fade as the gator grows.

There’s another crocodilian with a range that overlaps with that of the American alligator, the American crocodile. It’s usually paler in color than the alligator with a relatively narrow snout. It mostly lives in central America, but some do live in southern Florida, which makes southern Florida the only place in the world where gators and crocs live side by side in the wild. But crocodiles can’t tolerate cool weather as well as alligators, so cold snaps in Florida can kill off crocodiles while not harming alligators. Occasionally a big alligator will eat a smaller crocodile, but on average the croc is the bigger animal. Big males can occasionally grow over 20 feet long, or 6.1 meters. It frequently lives in salt water where it mostly eats fish and birds, along with small mammals, reptiles, amphibians, and crustaceans. It especially likes to eat lemon sharks. I mean, who wouldn’t, right? They sound delicious. Or maybe I just like lemons.

Unlike the American alligator, the American crocodile is endangered due to habitat loss, poaching, and pollution. It’s more dangerous to humans than the alligator, but not nearly as dangerous as some other species of crocodile.

The saltwater crocodile and the Nile crocodile are the most dangerous species to humans. The Nile crocodile can grow over 21 feet long, or almost 6.5 meters, and lives throughout much of Africa. The saltwater crocodile is the biggest crocodilian alive, and can grow up to 23 feet long, or 7 meters.

Like the American crocodile, the saltwater crocodile can tolerate salt water and frequently lives in coastal areas like the mouths of rivers, lagoons, and mangrove swamps. It’s found in parts of India down to northern Australia, and occasionally one will swim across the ocean to areas far from its usual range, including Japan and Fiji. Saltwater crocodiles, especially males, are territorial, and researchers think that about half of attacks on humans result from the human straying into a croc’s territory. These attacks aren’t usually fatal, but I bet they’re scary.

There are other crocodilians besides just the alligator and the crocodile. The gavial, also called the gharial or fish-eating crocodile, has a long, narrow snout that helps it catch the fish it eats. It lives in parts of India these days, in a few rivers and along the coasts, since it can tolerate salt water. It used to live throughout India and other parts of Asia, but it’s been hunted almost to extinction. In 1976 conservationists estimated that there were fewer than 200 gavials alive in the wild. Even after India put protections in place for the gavial, it continued to decline. In 2006 there were only 182 adult gavials alive. Conservationists are working hard to increase the population, including breeding them in captivity and releasing the babies into protected wildlife preserves in the wild. The main problems these days are loss of habitat and pollution, everything from dams across the rivers where it lives, heavy metal poisoning from polluted water, and drowning after entanglement in fishing nets. But population numbers have grown thanks to the conservation efforts, although there are probably fewer than 1,000 in the wild today.

The gavial can grow as long as the saltwater crocodile, although it’s usually much less heavy, with the longest measured at 23 feet long, or 7 meters. Adult males have a bulb at the end of their snouts that researchers think help them blow bubbles and make hissing and buzzing sounds that attract females.

Baby gavials eat tadpoles, frogs, and small fish. Adults eat fish and crustaceans. The gavial’s jaws are too delicate for it to feed on larger prey. In the past, hunters found jewelry in gavial stomachs and assumed they were maneaters, but it’s more likely they just swallowed jewelry lost in the river because it was shiny like fish scales.

There’s also a false gharial, which looks superficially like a gavial but has a broader snout. It’s reddish-brown with black splotches and some striping on the back and tail. These days it only lives in swamps in Indonesia and some nearby areas, although it used to have a broader range and also lived in rivers and lakes. Like the gavial, it’s been hunted to extinction in much of its former range for its skin and meat, and because people are afraid of it. It’s also vulnerable to habitat loss, including water pollution and draining of wetlands. It eats fish and other water animals, but it also preys on birds and mammals, and can grow more than 13 feet long, or 4 meters.

Caimans are most closely related to alligators and live in Central and South America. Some species are relatively small, from the 5 foot long, or 1.5 meter, Cuvier’s dwarf caiman, to the black caiman that can grow over 16 feet long, or 5 meters. Some researchers think the black caiman may occasionally grow up to 20 feet long, or 6 meters. Caiman scales are stiffened by calcium deposits, which makes caiman hide less valuable to leatherworkers than other crocodilian hides because it’s less pliable.

All crocodilians share an ancestor that lived around 240 million years ago. That same ancestor was also the ancestor of the dinosaurs. So it’s no surprise that crocodilians are considered the closest living bird relatives.

Paleontologists have discovered many extinct crocodilians, some of which look really strange. Mourasuchus, for instance, was a type of caiman that lived in South America during the Miocene, around 13 million years ago. Mourasuchus had long, flat jaws that looked something like a duck’s bill full of tiny conical teeth. Researchers think it may have been a filter feeder, filtering small animals from the mud at lake bottoms. But it was enormously big, some 39 feet long, or 12 meters.

Another possible filter feeding crocodilian was Stomatosuchus, which lived in Northern Africa around 95 million years ago and grew to 33 feet long, or 10 meters. It had a long, flat snout with small conical teeth in the upper jaw and may have had no teeth in the lower jaw. Some researchers think it might have had a pouched lower jaw like a pelican, which it used to catch small fish. It would suck in water, filling its pouch, then close its jaws and push the water out through its teeth. Any fish or other animals left in its mouth when all the water was expelled, it swallowed. But we don’t know for sure because only one Stomatosuchus skull has ever been found, and it was destroyed in 1944 when the museum it was in was bombed during World War II.

Purussaurus was another extinct caiman that lived in South America around 5 to 20 million years ago, and is estimated to grow as much as 41 feet long, or 12.5 meters. We don’t know its length for sure since we don’t have a complete skeleton, but if estimates are right, it was one of the biggest crocodilians that ever lived. It had a strong skull and huge teeth that allowed it to hold onto large prey.

Sarcosuchus was about the same size as Purussaurus, around 40 feet long, or 12 meters, but lived about 112 million years ago in what is now Africa and South America. It ate dinosaurs.

The largest living crocodilian ever reliably measured was a captive saltwater crocodile from the Philippines. He was captured in 2011 after rumors started that he had killed at least two people. He was kept on display in a wildlife center, and caretakers named him Lolong after one of the men who helped capture him. Lolong the crocodile was measured at 20 feet 3 inches long, or 6.17 meters, and he weighed 2,370 lbs, or 1,075 kg.

But crocodilians even larger than Lolong have been measured, just not by wildlife experts. Another saltwater crocodile in India has been estimated at 23 feet, or 7 meters, and a saltwater croc skull from Cambodia suggests that the living animal might also have been 23 feet long. A crocodile killed in Queensland, Australia in 1958 was supposedly 28 feet 4 inches long, or 8.64 meters, but this is probably an exaggeration.

But size is relative. A crocodilian that lived in South America some 60 million years ago and grew to a respectable 18 feet long, or 5.5 meters, probably got eaten by the largest known snake that ever lived, titanoboa. Titanoboa grew up to 42 feet long, or 12.8 meters. But that is a story for another day.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 075: Archelon and Other Giant Sea Turtles

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This week we’re going to find out about the biggest turtles that ever lived! Spoiler: one of them is alive right now, swimming around eating jellyfish.

A green sea turtle. These guys are adorable:

A hawkbill glowing like a neon sign!

The majestic and enormous leatherback:

Bebe leatherback. LET ME GOW

Seriously, how are baby sea turtles so darn cute?

Archelon was a big tortle:

Further reading:

This is a link to a pdf of that “Historicity of Sea Turtles Misidentified as Sea Monsters” article

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re back in the sea, but not the deep sea this time, because we’re looking at marine turtles!

The oldest known turtle ancestor lived around 220 million years ago, but it wouldn’t have looked a whole lot like a modern turtle. For one thing, it had teeth instead of a bill. It resembled a lizard with wide ribs that protected its belly. It lived in the ocean, probably in shallow inlets and bays, but it may have also spent part of its time on land. Some researchers think it may have had at least a partial shell formed from extensions of its backbone, but that this didn’t fossilize in the three specimens we have.

The oldest sea turtle fossil found so far has been dated to 120 million years old. It was seven feet long, or 2 meters, and already showed a lot of the adaptations that modern sea turtles have. Researchers think it was closely related to the green sea turtle and the hawksbill sea turtle.

Seven species of sea turtle are alive today. They all have streamlined shells and flippers instead of feet. They all breathe air, but they have big lungs and can stay underwater for a long time, up to about an hour while hunting, several hours when asleep or resting. Like whales, they surface and empty their lungs, then take one huge breath. They can see well underwater but can probably only hear low-frequency sounds.

Sea turtles have a special tear gland that produces tears with high salt concentration, to release excess salt from the body that comes from swallowing sea water. They migrate long distances to lay eggs, thousands of miles for some species and populations, and usually return to the same beach where they were hatched. Female sea turtles come ashore to lay their eggs in sand, but the males of most species never come ashore. The exception is the green sea turtle, which sometimes comes ashore just to bask in the sun. Once the babies hatch, they head to the sea and take off, swimming far past the continental shelf where there are fewer predators. They live around rafts of floating seaweed call sargassum, which protects them and attracts the tiny prey they eat.

Six of the extant sea turtles are relatively small. Not small compared to regular turtles, small compared to the seventh living sea turtle, the leatherback. More about that one in a minute. The other six are the green, loggerhead, hawksbill, Kemp’s ridley and Olive ridley, and the flatback.

Let’s start with the green sea turtle, since I just mentioned it. Its shell is not always green. It can be brown or even black depending on where it spends most of its life. Green turtles that live in colder areas of the Pacific have darker shells, which probably helps them stay warm by absorbing more heat from sunlight. Young turtles have darker shells than old turtles for the same reason.

The green sea turtle can grow up to five feet long, or 1.5 meters, can live some 80 years, and mostly eats plants, especially seagrass, although babies eat small animals like worms, jellyfish, and fish eggs. A recent satellite tracking study of green sea turtles in the Indian Ocean tracked the turtles to a huge underwater seagrass meadow that no human realized existed until then. The meadows were farther underwater than the ones researchers knew about, up to 95 feet deep, or 29 meters. Researchers think the seagrass can grow at these depths because the water is so clear in the area, which means more light for the plants.

Unlike the green sea turtle, which lives throughout much of the world’s oceans, the flatback sea turtle is only found around Australia. It’s greenish or grayish and only grows around 3 feet long, or 95 cm, and eats invertebrates of various kinds, including jellyfish, shrimp, and sea cucumbers. It stays near shore in shallow water and doesn’t migrate, so it’s mostly safe from getting tangled in commercial fishing nets that kill a lot of other sea turtle species.

The smallest sea turtle is the olive ridley, which only grows around two feet long, or 60 cm. Its shell is roughly heart-shaped and is usually olive green. It mostly lives in tropical waters and is the most common sea turtle of all the living species, but getting rarer. It likes warm, shallow water and eats small animals like snails, jellyfish, and sea urchins.

Kemp’s ridley sea turtle is closely related to the olive ridley, and is not much larger. It grows to around 28 inches long, or 70 cm, and eats the same things as the olive ridley. It also likes the same warm, shallow waters, but it nests exclusively along the Gulf Coast of North America. Oil spills in the Gulf have killed so many turtles that the species is now listed as critically endangered. Conservationists sometimes remove eggs to safer, cleaner beaches where babies are more likely to hatch and survive. Besides oil spills and other types of pollution, Kemp’s ridley sea turtles are often killed when they get tangled in shrimp nets and drown. Fortunately, shrimp trawlers in the Gulf now use turtle excluders, which help keep turtles from getting tangled.

The hawksbill sea turtle grows to around three feet long, or 1 meter, and lives around tropical reefs. It has a more pointed, hooked beak than other sea turtles, which gives it its name. You might think it eats fish or something with a beak like that, but mostly it eats jellyfish and sea sponges. It especially likes the sea sponges, some of which are lethally toxic to most other animals. It also doesn’t have a problem eating even extremely stingy jellies and jelly-like animals like the Portuguese man-o-war. The hawkbill’s head is armored so the stings don’t bother it, although it does close its eyes while it chomps down on jellies. People used to kill hawksbill sea turtles for their multicolored shells, but don’t eat them. Its meat can be toxic due to the toxins it ingests.

The hawksbill is also biofluorescent! Researchers only found this out by accident in 2015, when a team studying biofluorescent animals in the Solomon Islands saw and filmed a hawksbill glowing like a UFO with neon green and red light. Researchers still don’t know why and how the hawksbill glows. They think the red color may be emitted by certain algae that grow on hawksbill shells, but the green appears to be emitted by the turtle itself. Since the hawksbill lives mostly around coral reefs, where many animals biofluoresce, researchers hypothesize it might be a way for the turtle to blend in. If everyone’s glowing, the big turtle-shaped spot that isn’t glowing would give it away. Then again, since male turtles glow more brightly than females, researchers also think it may be a way to attract mates.

Finally, the loggerhead sea turtle grows to a little longer than three feet, or 95 cm, and its shell is usually reddish-brown. It lives throughout the world’s oceans and while it nests in a lot of places, many loggerheads lay their eggs on Florida beaches. It eats invertebrates like bivalves and sponges, barnacles and jellyfish, starfish, plants, and lots of other things, including baby turtles. Its jaws are powerful and it has scales on its front flippers that stick out a little, called pseudoclaws, which allow it to manipulate its food or tear it into smaller pieces.

All sea turtles are endangered and are protected worldwide, although some countries enforce the protection more than others. Some people still eat sea turtles and their eggs, even though both can contain bacteria and toxic metals that make people sick. But mostly it’s habitat loss, pollution, and fishing nets and longlines that kill turtles.

People want to build houses on the beach, or drive their cars on the beach, and that destroys the habitat female turtles need to lay their eggs. Turtles also get stuck in fishing equipment and drown. And there’s so much plastic floating around in the sea that all sorts of animals are affected, not just turtles. A floating plastic bag or popped balloon looks like a jellyfish to a sea turtle that doesn’t know what plastic is. A turtle can eat so much plastic that its digestive system becomes clogged and it dies. One easy way you can help is to remember your reusable bag when you go shopping. The fewer plastic bags that are made and used, the fewer will find their way into the ocean. Some countries have banned plastic shopping bags completely.

Now let’s talk about the leatherback turtle. It’s much bigger than the others and not very closely related to them. It can grow some nine feet long, or 3 meters, and instead of having a hard shell like other sea turtles, its carapace is covered with tough, leathery skin studded with tiny osteoderms. Seven raised ridges on the carapace run from head to tail and make the turtle more stable in the water, a good thing because leatherbacks migrate thousands of miles every year. Not only is the leatherback the biggest and heaviest turtle alive today by far, it’s the heaviest living reptile that isn’t a crocodile. It has huge front flippers, is much more streamlined even than other sea turtles, and has a number of interesting adaptations to life in the open ocean.

The leatherback lives throughout the world, from warm tropical oceans up into the Arctic Circle. It mostly eats jellyfish, so it goes where the jellyfish go, which is everywhere. It also eats other soft-bodied animals like squid. To help it swallow slippery, soft food when it doesn’t have the crushing plates that other sea turtles have, the leatherback’s throat is full of backwards-pointing spines. What goes down, will not come back up, which is great when the turtle swallows a jellyfish, not so great when it swallows a plastic bag.

The leatherback can dive as deep as 4,200 feet, or almost 1,300 meters. Even most whales don’t dive that deep. But it’s a reptile, so how does it manage to survive in such cold water, whether in the Arctic Ocean or nearly a mile below the water’s surface?

The leatherback’s metabolic rate is high to start with, and it swims almost constantly. Its muscles generate heat as they work, which keeps the turtle’s body warmer than the surrounding water, as much as 30 degrees Fahrenheit warmer, or 18 degrees Celsius. Its flippers and throat also use a system called countercurrent heat exchange, where blood that has been chilled by outside temperatures returns to the heart in veins that surround arteries containing warm blood flowing from the heart. By the time the cool blood reaches the heart, it’s been warmed by the arterial blood. This keeps heat inside the body’s core.

Unlike other sea turtle species, leatherbacks don’t necessarily return to the same beach where they were hatched to lay their eggs. Females usually nest every two or three years and lay about 100 eggs per nest. No one is sure how long leatherbacks live, but it may be a very long time. Most turtles have long lifespans, and many sea turtle species don’t even reach maturity until they’re a couple of decades old.

One interesting thing about sea turtles, which is also true of many other reptiles, is that the temperature of the egg determines whether the baby turtle will develop into a male or female. Cooler temperatures produce mostly male babies, warmer temperatures produce mostly female babies. This is pretty neat, until you remember that the global temperature is creeping up. A new study of sea turtles around Australia’s northern Great Barrier Reef found that almost all baby turtles hatching there are now female—up to 99.1% of all babies hatched. Another study found the same results in sea turtle nests in Florida, where 97 to 100% of all babies are female. The studies also found that the amount of water in the nest’s sand also contributes to whether babies are male or female, with drier nests producing more females. Researchers are considering incubating some nests in climate-controlled rookeries to ensure that enough males hatch and survive to produce the next generation.

So those are the seven types of sea turtle alive today. Now let’s talk about an extinct sea turtle, a relative of the leatherback. This is archelon, and it was huge.

Archelon was the biggest turtle that has ever lived, as far as we know. The first fossil archelon was discovered in 1895 in South Dakota, in rocks that were around 75 million years old. The biggest archelon fossil ever found came from the same area, and measures 13 feet long, or 4 meters. It’s even broader from flipper to flipper, some 16 feet wide, or 5 meters. It lived in the shallow sea that covered central North America during the Cretaceous, called the Western Interior Seaway. I like that name. Its shell was leathery and probably flexible like the leatherback’s, but unlike the leatherback, it wasn’t teardrop shaped. In fact, it was very round. Since it lived at the same time as mosasaurs, its wide shell may have kept it from being swallowed by predators. It probably ate squid and jellyfish like the leatherback, and researchers think it was probably a slow swimmer. It went extinct at the same time as the dinosaurs, but fortunately its smaller relations survived.

We don’t know if that 13-foot-long archelon was an unusually large specimen, an average specimen, or a small specimen. It was probably on the large size, but it’s a good bet that there were larger individuals swimming around 75 million years ago. We don’t know if leatherbacks occasionally get bigger than nine feet long, for that matter. But we do have reports of sea turtles that are much, much bigger than any sea turtles known.

In August of 2008, a 14-year-old boy snorkeling in Hawaii reported swimming above a sea turtle that was resting on the bottom of a lagoon. He estimated the turtle was eight to ten feet across with a round shell. At the time he didn’t realize that was unusual. He also reported seeing a geometric pattern on the shell, which is not a feature of the leatherback or archelon but is present in other sea turtles. So if his estimation of size is correct, he saw a sea turtle far bigger than any living today.

In 1833, a schooner off the coast of Newfoundland came across what they thought was an overturned boat. When the crew investigated, they discovered it wasn’t a boat at all but an enormous leatherback turtle, which they reported was 40 feet long, or 12 meters.

Many sea serpent sightings may actually be misidentifications of sea turtles. Sea turtles do have relatively long necks which they can and do raise out of the water. A long neck with a small head sticking out of the water, with a hump behind it, describes a lot of sea serpent reports. It’s also possible that some sea serpent reports are actually sightings of sea turtles entangled with fishing nets and other debris that the turtle drags with it as it swims, which may look like a long snake-like tail behind a humped body.

For instance, in 1934 some fishermen off the coast of Queensland, Australia spotted what they thought was a sea serpent. I’ll quote the description, which is from an article with the lengthy title of “Historicity of Sea Turtles Misidentified as Sea Monsters: A Case for the Early Entanglement of Marine Chelonians in Pre-plastic Fishing Nets and Maritime Debris” by Robert France. I’ll put a link in the show notes in case you want to read the article, if I can find it again. I printed it out so I could keep it.

Anyway, the fishermen reported that the sea serpent looked like this:

“The head rose about eight feet out of the water, and resembled a huge turtle’s head…the colour was greyish-green. The eye…was small in comparison to the rest of the monster. The other part in view was three curved humps about 20 feet apart, and each one rose from six feet in the front to a little less in the rear. They were covered with huge scales about the size of saucers, and also covered in barnacles. We could not get a glimpse of the tail, as it was under the water.”

Robert France suggests that this was a sea turtle entangled with a string of fishing gear, specifically fishing floats. He also gives a number of other examples dating back hundreds of years. Fortunately for sea turtles and other animals in the olden days, most fishing nets were made from rope, usually hemp and sometimes cotton, which eventually rotted and freed the animal, if it survived being entangled for months on end.

So if you live around the ocean, or any kind of water for that matter, make sure to pick up any litter you find, especially plastic bags. You could save a lot of lives. Who knows, maybe the sea turtle you save from eating that one fatal plastic bag will grow up to become the biggest sea turtle alive.

As a companion piece to this episode, Patreon subscribers got an episode about the Soay Island Sea Monster sighted in 1959, which was probably a sea turtle of some kind. Just saying.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 072: Weird Whales

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It’s been too long since we discussed whales, so this week let’s learn about how whales evolved and some especially strange or mysterious whales!

Pakicetus was probably kind of piggy-looking, but with a crocodile snout:

Protocetids were more actually whale-like but still not all that whale-like:

Now we’re getting whaley! Here’s basilosaurus, with a dinosaur name because the guy who found it thought it was a reptile:

Here’s the skull of a male strap-toothed whale (left). Those flat strips are the teeth:

Another view. See how the teeth grow up from the lower jaw and around the upper jaw?

A dead pygmy right whale:

The walrus whale may have looked sort of like this:

The half-beak porpoise had a chin that just would not quit:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week’s topic is weird whales and some of their relations. If you think about it, all whales are weird, but these are the weirdest whales we know of. Some are living, some are extinct, and some…are mysteries.

Whales, dolphins, and porpoises are most closely related to—wait for it—HIPPOPOTAMUSES. About 48 million years ago an ancestor of both modern hippos and whales lived in Asia. It’s called Inodhyus and it was about the size of a cat, but looked more pig-like. It was at least partially aquatic, probably as a way to hide from predators, but it was an omnivore that probably did most of its hunting and foraging on land.

The earliest whale is generally accepted to be Pakicetus. It lived around the same time as Inodhyus and its fossils have been found in what is now Pakistan and India. It was about the size of a big dog, but with a long, thick tail. Its skull was elongated, something like a short-snouted crocodile with big sharp triangular teeth. It had upward-facing eyes like a crocodile or hippo, and it also had four long, fairly thin legs. It probably hunted on both land and in shallow water, and like the hippo it probably didn’t have much hair.

That doesn’t sound much like a whale, but it had features that only appear in whales. These features became more and more exaggerated in its descendants. At first, these ancestral whales looked more like mammalian crocodiles. It’s not until Protocetids evolved around 45 million years ago that they started to look recognizably like whales. Some protocetids lived in shallow oceans throughout the world but probably still gave birth on land, while others were more amphibious and lived along the coasts, where they probably hunted both in and out of water. But they had nostrils that had migrated farther back up their snouts, although they weren’t blowholes just yet, reduced limbs, and may have had flukes on their large tails. But they still weren’t totally whale-like. One protocetid, Rodhocetus balochistanensis, still had nail-like hooves on its forefeet.

By around 41 million years ago, the basilosaurids and their close relations had evolved, and were fully aquatic. They lived in the oceans throughout the tropics and subtropics, and their nostrils had moved almost to the location of modern whales’ blowholes. Their forelegs were basically flippers with little fingers, their hind legs had almost disappeared, and they had tail flukes. They were also much bigger than their ancestors. Basilosaurus could grow up to 60 feet long, or 18 meters, and probably looked more like a gigantic eel than a modern whale. It was long and relatively thin, and may have mostly lived at the ocean’s surface, swimming more like an eel or fish than a whale. It ate fish and sharks. SHARKS.

So when did whales develop the ability to echolocate? Researchers think it happened roughly 34 million years ago, which also happens to be about the same time that baleen whales and toothed whales started to develop separately. Echolocation probably evolved to help whales track hard-shelled mollusks called nautiloids. By 10 million years ago, though, nautiloids were on the decline and mostly lived around reefs. Whales had to shift their focus to soft-bodied prey like squid, which meant their sonar abilities had to become more and more refined. Toothed whales echolocate, while baleen whales probably do not. Researchers aren’t 100% sure, but if baleen whales do use echolocation, it’s limited in scope and the whales probably mostly use it for sensing obstacles like ice or the sea floor.

Baleen whales are the ones that communicate with song, although the really elaborate songs are from humpback and bowhead whales. Of those species, humpback songs are structured and orderly, while bowhead whale song is more free-form. But humpback songs do change, and researchers have discovered that they spread among a population of whales the same way popular songs spread through human populations. This is what they sound like, by the way. A snippet of humpback song is first, then a snippet of bowhead song.

[examples of humpback and bowhead]

So now we’ve got a basic understanding of how whales evolved. Now let’s take a look at some of the weirder whales we know about. We’ll start with a living one, the strap-toothed whale. It’s one of 20-odd species of mesoplodont, or beaked whale, and we don’t know a whole lot about any of them. The strap-toothed whale is the longest beaked whale at 20 feet long, or 6.2 meters.

The strap-toothed whale lives in cold waters in the southern hemisphere. It’s rarely seen, probably since it lives in areas that aren’t very well traveled by humans. It mostly eats squid. Females are usually a little bigger than males, and adults are mostly black with white markings on the throat and back.

The weird thing about this whale is its teeth. Male beaked whales all have a pair of weird teeth, usually tusk-like, which they use to fight each other, but strap-toothed whales take the weird teeth deal to the extreme. As a male grows, two of its teeth grow up from the lower jaw and backwards, curving around the upper jaw until the whale can’t open its mouth very far and can only eat small prey. The teeth can grow a foot long, or 30 cm, and have small projections that cause more damage in fights with other males.

Most of what we know about the strap-toothed whale comes from whales that have been stranded on land and died. Males don’t seem to have any trouble getting enough to eat, and researchers think they may use suction to pull prey into their mouths. Other beaked whales are known to feed this way.

All beaked whales are deep divers, generally live in remote parts of the world’s oceans, and are rarely seen. In other words, we don’t know for sure how many species there really are. In 1963, a dead beaked whale washed ashore in Sri Lanka. At first it was described as a new species, but a few years later other researchers decided it was a ginkgo-toothed whale, which had also only been discovered in 1963. Male ginkgo-toothed whales have a pair of tusks shaped like ginkgo leaves, but they don’t appear to use them to fight each other. But a study published in 2014 determined that the 1963 whale, along with six others found stranded in various areas, belong to a new species. It’s never been seen alive. Neither has the ginkgo-toothed whale.

The pygmy right whale is a baleen whale, but it’s another one we know very little about. It lives in the southern hemisphere. Despite its name, it isn’t closely related to the right whale. It’s small for a baleen whale, around 21 feet long, or 6.5 meters, and it’s dark gray above and lighter gray or white underneath. Its sickle-shaped dorsal fin is small and doesn’t always show when the whale surfaces to breathe. It feeds mostly on tiny crustaceans like copepods, and probably doesn’t dive very deeply considering its relatively small heart and lungs.

The pygmy right whale was first described in 1846 from bones and baleen. Later studies revealed that it’s really different from other baleen whales, with more pairs of ribs and other physical differences. It also doesn’t seem to act like other baleen whales. It doesn’t breach, slap its tail, or show its flukes when it dives. It doesn’t even swim the same way other whales swim. Other whales swim by flexing the tail, leaving the body stable, but the pygmy right whale flexes its whole body from head to tail. It seems to be a fairly solitary whale, usually seen singly or in pairs, although sometimes one will travel with other whale species. In 1992, though, 80 pygmy right whales were seen together off the coast of southwest Australia. Fewer than 200 of the whales have been spotted alive, including those 80, so we have no idea how rare they are.

It wasn’t until 2012 that the pygmy right whale’s differences were explained. It turns out that it’s not that closely related to other baleen whales. Instead, it’s the descendant of a family of whales called cetotheres—but until then, researchers thought cetotheres had gone extinct completely around two million years ago. Not only that, it turns out that at least one other cetothere survived much later than two million years ago, with new fossils dated to only 700,000 years ago. But that particular whale, Herpetocetus, had a weird jaw joint that kept it from being able to open its mouth very far. It and the strap-toothed whale should start a club.

Sometimes whale fossils are found in unexpected places, which helps give us an idea of what the land and ocean was like at the time. For instance, fossils of an extinct beaked whale known as a Turkana ziphiid was found in Kenya in 1963, in a desert region 460 miles inland, or 740 kilometers. The fossil is 17 million years old. So how did it get so far inland?

It turns out that at the time, that part of east Africa was near sea level and grown up with forests. The fossil was found in river deposits, so the whale probably swam into the mouth of a river, got confused and kept going, and then couldn’t turn around. It kept swimming until it became stranded and died. Because of the finding, researchers know that 17 million years ago, the uplift of East Africa had not yet begun, or if it had it hadn’t yet made much progress. The uplift, of course, is what prompted our own ancestors to start walking upright, as their forest home slowly became grassland.

As an interesting aside, the fossil was stored at the Smithsonian, but at some point, like so many other fascinating items, it disappeared. Paleontologist Louis Jacobs spent 30 years trying to find it, and eventually located it at Harvard University in 2011. After he finished studying it, he donated it to the National Museum of Kenya.

More whale fossils were uncovered in 2010 in the Atacama Desert in Chile—in this case, over 75 skeletons, many in excellent condition, dated to between 2 and 7 million years ago. Researchers think they’re the result of toxic algae blooms that killed the whales, which then washed ashore. Over 40 were various types of baleen whales. Other fossils found in the same deposit include a sperm whale, marine sloths, and a tusked dolphin known as a walrus whale.

The walrus whale lived in the Pacific Ocean around 10 million years ago, and while it’s considered a dolphin, it’s actually more closely related to narwhals. But it probably looked more like a walrus than either. Unlike most whales, it had a flexible neck. It also had a face like a walrus. You know, flattish with tusks sticking down. It probably ate molluscs. But the right tusk was much longer than the left one, possibly in males only. In the case of one species of walrus whale, one specimen’s left tusk was about 10 inches long, or 25 cm, while its right tusk was over four feet long, or 1.35 meters. Some researchers suggest that the whale swam with its head bent so that the long tusk lay along the body. Possibly it only used it for display, either to show off for females or to fight other males. But we don’t know for sure.

Speaking of narwhals, if you were hoping to hear about them, you’ll need to go way back to episode five, about the unicorn. I talk about the narwhal a lot in that episode. The narwhal happens to be one of the best animals. A lot of people think the narwhal isn’t a real animal, that it’s made up like a unicorn. In fact, about a week ago, I was talking to a coworker and the subject of narwhals came up. She actually did not realize it was a real animal. Nope, it’s real, and that horn is real, but it’s actually a tusk rather than a horn. It grows through the whale’s upper lip, not its forehead. In another weird coincidence, this afternoon when I was about to sit down and record this episode, a friend sent me a link to an article that had some narwhal sounds. So we’re not really talking about narwhals in this episode, but hey, this is what they sound like.

[narwhal calls]

Another weird whale is the halfbeak porpoise, or skimmer porpoise, which lived off the coast of what is now California between 5 and 1.5 million years ago. While it probably looked mostly like an ordinary porpoise, its chin grew incredibly long. The chin, properly called a symphysis, was highly sensitive, and researchers think it used it to probe in the mud for food.

There’s still so much to learn about whales, both living ones and extinct ones. We definitely haven’t identified all the living whales yet. There are reports of strange whales from all over the world, including a baleen whale with two dorsal fins. It was first spotted in 1867 off the coast of Chile by a naturalist, and other sightings have been made since. It’s supposedly 60 feet long, or 18 meters, so you’d think it wouldn’t be all that hard to spot…but there’s a whole lot of ocean out there, and relatively few people on the ocean to look for rare whales.

Whales can live a really long time. In 2007, researchers studying a dead bowhead whale found a piece of harpoon embedded in its skin. It turned out to be a type of harpoon that was made around 1879. Bowheads can probably live more than 200 years, and may even live longer than that.

And, of course, whales are extremely intelligent animals with complex social and emotional lives, the ability to reason and remember, tool use, creative thinking and play, self-awareness, a certain amount of language use, and altruistic behaviors toward members of other species. Whales and dolphins sometimes help human swimmers in distress, dolphins and porpoises sometimes help beached whales, and humpback whales in particular sometimes rescue seals and other animals from orcas. Humans aren’t very good at thinking about intelligence except as it pertains to us, but it seems pretty clear that other apes, whales and their relations, elephants, and probably a great many other animals are a lot more intelligent than we’ve traditionally thought.

One last interesting fact about whales and their relations. Most of them sleep with half their brain at a time. The half that isn’t sleeping takes care of rising to the surface to breathe periodically, so the whale doesn’t drown. That does not sound very restful to me. But sperm whales sleep with their bodies vertical and their heads sticking up out of the water. But they don’t sleep very long, only around ten minutes at a time—and only in the hours before midnight. I’ve had nights like that.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!