Category Archives: dinosaurs

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 066: TYRANNOSAURUS REX

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Thanks to Damian, who suggested T. rex as a topic! Let’s learn all about the T. rex and especially the most famous and controversial specimen ever found, Sue.

A T. rex:

Sue, also a T. rex:

Show transcript:

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

Our topic this week is a suggestion from Damian, who wants to hear about the one, the only, the tyrant lizard king with massive everything except arms, Tyrannosaurus rex. Aw yeah

You probably know a lot about T. rex without realizing it. It’s THE dinosaur, the one people think of first when you say dinosaur. But a lot of popular knowledge about the T. rex is actually out of date, so let’s find out what’s really going on with that big toothy theropod.

First of all, T. rex did not live in the Jurassic period. It lived much later, in the late Cretaceous, around 66 million years ago. But I guess Late Cretaceous Park doesn’t have quite the same ring to it. It was one of the last non-avian dinosaurs, dying off in the Cretaceous-Paleogene extinction. It lived in what is now western North America, with close relatives in many other parts of the world.

T. rex was a big animal, no doubt about it. The biggest individual we know of, called Sue, stood around 12 feet tall, or a little over 3 ½ meters at the hips. The weight of its massive head was balanced by its long tail. Nose to tail it was around 40 feet long, or about 12 meters. Plenty of other dinosaurs were bigger than T. rex, but T. rex was the biggest land predator we know of.

While T. rex had long legs, its arms are famously teeny, only about three feet long, or one meter. That’s barely longer than an adult human’s arm. But recent research shows that the arms weren’t weak. The bones were strong and so were the muscles, although the arm had a limited range of motion and only two toes. Many researchers think T rex used its arms to hold onto struggling prey.

Since all we have are fossils, we don’t really know what T. rex looked like beyond its bones and muscles, which we know about from study of muscle attachment sites on the bones. Some researchers think it probably had at least some feathers, since we have feather impressions from some of T rex’s close relations. Baby T rex might have had feathers and shed them as it grew up, or it might have had feathers its whole life. We have fossilized skin impressions from a specimen found in 2002 that show scales on the tail, neck, and hip, so many researchers suggest that T rex only had feathers on its head and back, possibly for decoration or protection from the elements. Closely related species show feather impressions over all of the body, so we know T rex’s cousins were feathered.

We also know that T rex had large flat scales on its snout with patches of keratin in the middle, which probably contained sensory bundles. These same patches are present in crocodilians, which help crocs move their eggs and babies without harming them, and help them sense the temperature of their nests.

In 2016, researchers discovered that T rex’s teeth contained enamel. This makes the teeth harder, but enamel has to stay damp. That means T rex probably had lips and its teeth wouldn’t have been visible except when the mouth was open. If that sounds weird, most reptiles have lips. Crocodilians don’t, so some of their teeth show when their mouths are closed, but they also live in the water so don’t have to worry about dry mouth.

Just to be clear, reptile lips aren’t big kissy lips. They’re just skin that allows the teeth to be completely enclosed within the mouth when the jaws are closed, keeping the mouth from drying out.

In 2005, paleontologist Mary Schweitzer found soft tissue in the femur, or thigh bone, of a 68 million year old T rex. The tissue contained blood vessels and a substance called medullary bone, which is only present in female birds right before they lay eggs. Medullary bone helps the bird’s body make shells for her eggs. Since then, researchers have found soft tissue within bones of two more T rexes and a hadrosaur. They’re not yet sure how the soft tissue was preserved. The blood vessels resemble those of ostriches more than they resemble crocodilian blood vessels.

For a long time scientists thought that dinosaurs like T rex stood upright with the tail acting as a prop. You know, sort of like Barney. This was recognized as wrong by around the 1970s, but paleontologists are still figuring out the details about how T rex moved around. For instance, we still don’t know if T rex could run. Many researchers now think it probably could, although it might not have been able to run faster than around 25 mph, or 40 km/h. That’s about the speed of a human sprinter. Some of T rex’s bones are hollow to reduce weight, and its feet show adaptations to withstand stresses. But we don’t know for sure, and studies continue using ever more sophisticated mathematical models.

We also don’t know if T rex was warmblooded like birds, or cold-blooded like reptiles. Considering its close relationship to birds, many researchers think it was warm-blooded, properly called endothermic. An endothermic animal can regulate its body temperature internally regardless of the air temperature.

T rex had excellent vision and sense of smell. It could hear very well too, especially low-frequency sounds. It had a massively strong bite, probably the strongest bite force of any land animal. Its bite could crush bone. It would have been a deadly hunter but probably also scavenged, either by stealing kills from other predators or eating anything dead it came across.

We have fossils that show damage from T rex bites, including to other T rexes. It’s possible T rexes fought, either over food or mates, or that bigger T rexes sometimes ate smaller ones. All T rex remains show damage, though, since the life of a predator is a tough one, and the bigger the animals you hunt, the more damage you’re going to take.

So that’s a lot of up-to-date information about Tyrannosaurus rex, or as up-to-date as I could find. Lots of paleontologists are studying T rex, so more information gets published all the time. While I was researching, though, I kept running across interesting details about the specimen nicknamed Sue.

Sue was discovered in August 1990 in South Dakota, on the Cheyenne River Indian Reservation, by paleontologist Sue Hendrickson. It was the last day of the dig and in fact the group was about to head home with a bunch of Edmontosaurus fossils when they noticed their truck had a flat tire. While the tire was getting changed, Sue Hendrickson took the opportunity to poke around for any last-minute fossils. She spotted some loose bones that had weathered out of a cliff, and saw bigger bones sticking out of the cliff above her, so she took the loose bones back to the dig supervisor and president of the Black Hills Institute, Peter Larson. Larson recognized them as T rex bones and immediately decided they weren’t going to leave that day after all.

It was a good decision, because once the bones were excavated, it turned out to be not only the biggest T rex skeleton ever discovered, but the most complete, and in excellent condition.

The group took the fossils back to the Black Hills Institute to clean and prepare them, and that should have been that. But unfortunately, T rex remains are worth a lot of money and that caused issues almost immediately.

The Black Hills Institute had gotten permission to excavate Sue the dinosaur, and had paid the landowner $5,000. The land was owned by Maurice Williams, a member of the Sioux tribe, and since his land was also part of the Sioux reservation, the tribe said the fossils belonged to the tribe, not just Williams.

It’s easy to think of Williams as greedy, but the situation was far more complicated than it sounds. Peter Larson’s group weren’t just in it for the science. They were commercial bone hunters, which means they would have sold the T rex fossil after it was prepared and kept all the money. They had already started taking offers for the sale when Williams sued. Not only that, Williams’s land was held in trust by the government, which meant Larson was supposed to get permission from not just Maurice Williams but the Department of the Interior to excavate fossils on the land, and he hadn’t even asked.

It was a lengthy, complicated trial. Even the FBI had to get involved. They and the South Dakota National Guard seized the fossils and kept them in storage until the trial ended. Peter Larson was charged with fossil theft—not of Sue the T rex, but of other fossils that didn’t have anything to do with Williams. He was found guilty of theft of fossils from public land and lying on customs documents about fossil deals in Peru and Japan, and spent 18 months in jail.

The court decided that Maurice Williams did own the fossils. Williams contacted the auction house Sotheby’s to sell them.

The paleontological community panicked at this, because when I say T rex fossils are worth a lot of money, I don’t mean it’s just scientists who fight each other to buy them. I mean rich people want them for private collections. Fossils in private collections are usually never studied, so they’re nothing more than decorations and don’t add anything to our collective knowledge of creatures that lived in the past. There’s nothing wrong with owning fossils of common animals, of course, but when it’s an important find like this one, it needs to be prepared properly, studied by experts all over the world, and put on public display.

So the Chicago Field Museum of Natural History scrambled to find funding to bid on the T rex. They asked lots of companies and individuals to donate, and those companies and individuals stepped up—companies like McDonald’s and Walt Disney Parks, so good for them.

The auction was held in October 1997. The starting bid was $500,000. At the time, the top amount paid for a fossil had been around $600,000, but Sotheby’s expected this sale to top one million. We don’t know who bid because Sotheby’s keeps this information a secret, but we do know that the Smithsonian had been prepared to spend 2 ½ million.

The auction only lasted eight minutes and the Field Museum won. It paid $8.3 million dollars for Sue the T rex, of which 7.6 million went to Williams. Disney was given a replica of Sue’s skeleton for display and McDonald’s was given two replicas.

It’s great that Sue was bought by an institution that has made the fossil available for study and put it on permanent display to the public. But because the auction went for so much, and was so well publicized, it had some negative repercussions. For a few years after the auction, all fossil auctions were much higher than before, stretching museum budgets to the limits. It is now much harder for paleontologists to get permission to dig on private property, and people started stealing fossils from dig sites, thinking they might get rich.

Williams was fined for selling dinosaur bones without a business license. He died in 2011 at the age of 85and I couldn’t find out what he did with the money he received from the auction, but apparently he kept it in his family and did not donate any to his tribe. While the Cheyenne River tribe’s policy is to leave fossils undisturbed, the nearby Standing Rock Reservation has its own paleontology department and museum. The group visits local schools to give presentations on dinosaurs found in the area.

In 2002 Larson and his then-wife, Kristin Donnan, published a book called Rex Appeal, and in 2014 made a documentary from the book called Dinosaur 13. Critics have pointed out that both book and film tell a one-sided story, painting Larson as an innocent who was wronged by the system and ignoring Williams’s point of view entirely.

It sounds like Williams was actually kind of a jerk. But it also sounds like Larson was kind of a jerk. People get weird when a lot of money is on the line, and at least Larson truly loves paleontology and has contributed a lot to the field—you know, when he’s not selling fossils to private collectors.

As for Sue the T rex, we don’t actually know if the dinosaur was male or female, but it usually gets referred to as a she because it’s named after Sue Hendrickson, the discoverer. Sue the T rex has been studied extensively so we know a lot about her. She was 28 years old when she died and had arthritis in her tail, had recovered from some serious injuries including broken ribs and a torn tendon in her right arm, and her skull shows pathology that might have killed her. Some researchers think Sue died from a parasitic infection from eating diseased meat. Modern birds sometimes contract what may be the same parasite, which causes swelling of the throat that ultimately starves the bird to death.

A few months ago as of this recording, in February of 2018, Sue was dismantled and removed temporarily from display so that some missing small bones can be added to the skeleton and adjustments made to her posture. She will then be moved to her own room in the Field Museum in 2019. Sue also has her own Twitter account, @SUEtheTrex. It’s actually pretty funny. I just followed it.

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 050: Tallest Animals

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We’re discovering which animals are the tallest this week! This episode includes our first dinosaur!

Sauroposeidon proteles:

Giraffes:

Bop bop bop have at thee!

Paraceratherium (I couldn’t find one that I liked so I drew one, along with a giraffe and ostrich to scale):

Ostrich running:

I SAID DON’T @ ME

A fine day at the ostrich races. I could not make this stuff up if I tried:

Show transcript:

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

This week we’re looking at tall animals. Is the giraffe the tallest mammal that’s ever lived? Is the ostrich the tallest bird? And what about tall dinosaurs?

I don’t talk about dinosaurs much in this podcast because there are so many good podcasts devoted specifically to dinosaurs. I recommend I Know Dino. It’s family friendly and goes over the latest dinosaur news without talking down to listeners or dumbing down the information.

Four-footed animals are usually measured at the shoulder, since some animals hold their heads low, like bison, while others hold their heads high, like horses. But we’re talking about tall animals today, and that includes animals with long necks. So the measurements here are all from head to toe, with the head and neck held in its natural standing position.

Let’s start with the real biggie, the tallest dinosaur ever found.

In 1994 a guy named Bobby Cross noticed some fossils weathering out of the ground at the Oklahoma correctional facility where he worked as a dog trainer. As he always did when he found fossils, he called the Oklahoma Museum of Natural History. They sent a team to take a look. The team found four vertebrae, but they were just so big—around four feet long each, or 120 cm—that at first they thought they must be fossilized tree trunks.

Sauroposeidon proteles was probably closely related to Brachiosaurus, but was even bigger and taller. Sauroposeidon stood 60 feet tall, or 18 meters, and its neck alone was 39 feet long, or 12 meters. Its body and legs were relatively short and stocky. We don’t have a complete skeleton, just the four vertebrae found in southeastern Oklahoma, and a few vertebrae from two other individuals found in Montana and Texas. A trail of giant footprints in Texas may be a Sauroposeidon track too. But for sauropods, neck vertebrae are the most valuable fossils because they tell so much about the animal.

Sauroposeidon’s neck bones were massive, but they were lighter than they look due to tiny air sacs in the bones, like those in bird bones. The air sacs in bird bones actually contain air that flows through the lungs, called pneumatic bones, which provides the bird with more oxygen. A CT scan of the Sauroposeidon fossils—at least the portions of the fossils that would actually fit in the CT scanner—revealed that sauroposeidon’s vertebrae were constructed in the same way that bird bones are. We know that pterosaurs and theropods had pneumatic bones, so it’s not too surprising that at least some sauropods did too.

Sauroposeidon lived around 110 million years ago, during the Mesozoic era, specifically during the early to mid Cretaceous. The sea level was much higher then than it is now, so Sauroposeidon lived near the coast. It ate plants, and like many birds, it also swallowed stones to help it digest those plants, called gastroliths. Paleontologists have found lots of sauropod gastroliths associated with fossil animals. Unlike mammals, which chew their food before swallowing, sauropods swallowed it whole and the plant material was broken up in a stomach or gizzard-like structure. That’s why its head is so small relative to its body, and how it could eat enough plants to keep such an enormous body going. It probably ate literally a ton of food every single day.

We know a lot about sauropods, and since sauroposeidon appears to be structurally typical of other sauropods, just really big, it’s a safe bet to assume it was like other sauropods in many ways. It probably nested in groups and laid about two dozen eggs at a time in big nests on the ground. We don’t have any sauroposeidon eggs, but they probably wouldn’t have been all that big, maybe about the size of a football. Babies would have grown rapidly and were full grown in ten to twenty years. Sauroposeidon migrated in herds throughout the year, traveling from nesting grounds to new grazing grounds. While it lived near the ocean, it would have had to be careful about walking on soft ground. An animal that tall and heavy can get mired in mud easily. Paleontologists have actually found fossils of sauropods that died standing up, unable to climb out of a muddy hole after sinking in soft ground.

Giraffes are the tallest living animals today, with the tallest recorded giraffe, a male, measuring 19.3 feet, or 5.88 meters. That’s pretty darn tall, about 1/3 the height of sauroposeidon. Giraffes are related to deer and cattle, and live in the savannahs and forests of Africa, where they eat tree leaves that are much too high off the ground for other animals to reach. Female giraffes and their young make up loose groups, while males form groups of their own. While giraffes can kick hard enough to kill lions, when males fight over females, they use their necks. A male will swing its head at another male, and the two will tussle back and forth bopping necks together. As a result, male giraffes have thicker, stronger necks than females. Males are also usually taller than females.

The giraffe not only has a long neck and long legs, it has a long tongue that it uses to grab leaves that are juuuust too far away. The tongue is about 18 inches long, or 45 cm. A giraffe at Knoxville Zoo licked my hair once. The giraffe’s upper lip is also prehensile, and is hairy as a protection from thorns. Because of all the thorns it encounters, giraffe skin is surprisingly tough. The giraffe has large eyes that give it good vision, and it also has keen hearing and smell. It can close its nostrils to protect them from dust, sand, insects, and—you guessed it—thorns. So many thorns. And giraffe fur contains natural parasite repellents, which also makes giraffes smell funny.

All this is pretty awesome, but we’re not done with giraffe awesomeness. Giraffes have skin-covered horns called ossicones. Females and males both have ossicones, although males also have a median lump at the front of the skull that’s not exactly an ossicone but is sort of like one. Some females also have this median lump. Ossicones are made of cartilage that has ossified, or turned boney, and they’re covered in skin and hair, although since males use their ossicones in necking fights, they tend to rub all the hair off and have bald ossicones.

The only other animal alive today that has ossicones is the okapi, a close relative of the giraffe, but giraffe ancestors once had all kinds of weird ossicones. Xenokeryx amidalae, for instance, which lived about 16 million years ago in what is now Spain, had two ossicones over its eyes, and a third sticking up from the back of its head that was T-shaped. The name amidalae comes from the character Padme Amidala in Star Wars: The Phantom Menace, if you remember that weirdly shaped headdress she wore.

Because giraffes are so tall, they have some physical adaptations that are unique among mammals living today. A giraffe has the same number of neck bones as all other mammals except sloths and manatees, which are weird, but the vertebrae are much longer than in other mammals, almost a foot long, or 28 cm. The giraffe can also tilt its head right back until it’s just about in line with the back of the neck. I’m picturing everyone listening tilting their heads back right now, and hopefully you notice how the back of your neck curves when you look up. Also, please don’t wreck your car because you’re looking up while driving. The giraffe’s circulatory system is really unusual. Its heart is enormous and beats around 150 times per minute. The jugular veins, which are the big veins that carry blood up the neck to the brain, have valves that keep blood from running backwards when a giraffe lowers its head to drink.

Giraffes can walk, and giraffes can run, but they don’t have any other gaits. They can’t trot or canter, for instance. Even humans have more than two gaits, because we can skip. Despite its height, a giraffe can really move. It can run over 30 miles per hour, or about 50 km per hour, and keep it up for several miles. It has cloven hooves. Because a giraffe’s body is so heavy and its legs so long and thin, it has specialized ligament structures in its legs that keep them from collapsing. Horses also have this structure, which also helps the animal sleep while standing.

Oh, and the giraffe doesn’t eat leaves all the time. It spends a lot of the day just standing around chewing its cud.

There used to be a mammal that stood almost as tall as the giraffe at the shoulder. Paraceratherium orgosensis went extinct around 23 million years ago, and it’s not even related to the giraffe. It’s a member of the rhinoceros family. Like sauroposeidon, we don’t have a complete skeleton of paraceratherium, so its size is an estimate based on the proportions of closely related animals whose sizes we do know. It probably stood 18 feet high at the shoulder, or 5.5 meters, and while its neck was probably around 7 feet long, or a little over 2 meters, it probably held it forward like a rhino instead of up like a giraffe, so it didn’t add much to the animal’s overall height.

In episode 32 we learned about the giant moa, a flightless bird that once lived in New Zealand. It was probably the tallest bird that ever lived, with big females 12 feet tall, or 3.6 meters. But the tallest living bird is the ostrich. It also lives in Africa and is famous for being flightless and for being able to run really fast. In fact, it’s not only the tallest bird alive, it’s the fastest. It can run over 40 miles per hour, or about 70 km per hour, and it uses its large wings as rudders and even to help it brake. With its head raised, a big ostrich can be nine feet tall, or 2.8 meters.

There are a lot of differences between ostriches and most other birds. Most birds have four toes, for instance. The ostrich has two, one large toe with a hoof-like nail, and a smaller outer toe with no nail at all. All other living birds secrete urine and feces together, but the ostrich secretes them separately the way mammals do. And while most male birds don’t have a penis, the male ostrich does. And the ostrich has a double kneecap. Not only is that unique to birds, it’s unique to everything. No other animal known, living or extinct, has a double kneecap. Researchers have no idea what it’s for, although one hypothesis is that it allows a running ostrich to extend its legs farther, and another hypothesis is that it might protect tendons in the bird’s leg.

The ostrich eats plants, seeds, and sometimes insects. Like Sauroposeidon and many other dinosaurs and birds, the ostrich swallows small rocks and pebbles to help digest its food in its gizzard. The gizzard contracts, smashing the gastroliths and plants together to help break up the plant material the way mammals would chew it.

Ostrich eggs are the biggest laid by any living bird, about six inches long, or 15 cm. Females lay their eggs in a communal nest.

Ostriches are farmed like big chickens, for their feathers, meat, and skin for leather. Ostriches are also sometimes ridden and raced with special saddles and bridles. But ostriches aren’t easy birds to manage. They can be aggressive, and they can kill a human with one kick.

To wrap things back around to dinosaurs, some researchers think many fast-running dinosaurs used their feathered forelimbs the way ostriches use their wings, to help maneuver and possibly to help keep unfeathered portions of the body warm at night. During the day, when it’s hot, ostriches keep their wings raised so that their unfeathered upper legs can release heat into the atmosphere, but at night they cover their upper legs to retain heat. It’s just another link between birds and their long-distant ancestors, the dinosaurs.

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!