Category Archives: fossils

Episode 132: Paleontological Frauds

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Ever heard of the Piltdown Man? What about Missourium or Archaeoraptor? They’re all frauds! Let’s learn about them and more this week.

Further reading:

The Chimeric Missourium and Hydrarchos

Investigation of a claim of a late-surviving pterosaur and exposure of a taxidermic hoax: the case of Cornelius Meyer’s dragon

Missourium was literally an extra mastodon:

Hydrarchos (left) was a lot more, um, exciting than its fossil donors, six Basilosauruses (right):

Piltdown man’s suspicious skull:

A lot of people were excited about Archaeoraptor:

Not a pterosaur:

Show transcript:

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

Last week we learned about some mistakes paleontologists made while working out what an extinct animal looked like using only a few fossilized bones. Mistakes are a normal part of the scientific method, no matter how silly they seem once we know more about the animal. But this week we’re going to look at some frauds and hoaxes in the paleontology world.

We really need to start with a man named Albert Koch. He was from Germany but moved to the United States in 1835, and was something of a cut-rate PT Barnum. He called himself Dr. Koch although he hadn’t earned a doctorate. A lot of the so-called curiosities he displayed were fakes.

Back in the mid-19th century, fossils had only recently been recognized as being from animals that lived millions of years before. People were still getting their heads around that concept, and around the idea that animal species could even go extinct. Then the fossils of huge animals started to be discovered—and not just discovered, but displayed in museums where the public could go look at them. Naturally they were big hits.

Sometimes these fossil exhibits weren’t free. For example, the mounted fossil skeleton of a mastodon was exhibited by the naturalist Charles Peale starting in 1802—one of the first fossil exhibits open to the public. Peale and his workers had mounted the skeleton to seem even larger than it really was by putting wooden discs between some of the bones. But the exhibit was primarily meant to educate, not just bring in money. It cost 50 cents to see the mastodon and lots of people wanted to. These days Peale’s mastodon is on display in Germany, without the wooden discs.

Albert Koch knew about Peale’s mastodon, and more to the point he knew how much money Peale had made off his mastodon. Koch wanted one for himself.

In 1840 he heard about a farmer in Missouri who had dug up some huge bones. Koch bought the bones and assembled them into a mastodon. But Koch wasn’t a paleontologist, he didn’t care about educating the public, and when he looked at those fossils, he just saw dollar signs. And he had ended up with bones from more than one mastodon, so, you know, he used them all. And he added wooden discs between the bones to make the animal bigger. A lot bigger. Between the wooden discs and the extra bones, Koch’s skeleton was twice the size of a real mastodon. Plus, he turned the tusks around so that they pointed upward, either because he didn’t know any better or because he thought that looked more exciting.

He called his mastodon Missourium and displayed it at his exhibit hall in St. Louis, Missouri later in 1840. It was a hit, and in 1841 he decided he’d make more money if he took Missourium on the road. He packed the massive skeleton up, sold his exhibit hall, and went on tour with just the mastodon.

Paleontologists spoke out against Koch’s Missourium as being unscientific, but that only gave him free publicity. People thronged to his exhibit for the next two years, until 1843 when he sold it to the British Museum. Needless to say, the experts at the British Museum promptly disassembled Missourium so they could study the fossils properly before remounting them into a mastodon that didn’t contain any extra ribs and vertebrae. Also, they put the tusks on the right way up.

But Koch wasn’t done riding roughshod over paleontology. To learn about what he did next, we have to learn about an animal called Basilosaurus.

Despite its name, Basilosaurus isn’t a dinosaur or even a reptile. It’s a mammal—specifically a whale, although it didn’t look like any whale alive today. It probably grew up to 70 feet long, or over 21 meters, with long jaws full of massive teeth—more like a crocodile or mosasaur than a whale. It had short flipper-like front legs that still had an elbow joint. Modern whales don’t have elbows. It also had little nubby hind legs, but the legs were far too small to support its weight on land. It probably mostly lived at or near the surface of the ocean since its vertebrae were large, hollow, and filled with fluid, which would have made Basilosaurus buoyant. It wouldn’t have been able to dive much at all as a result. It ate sharks and fish as well as smaller whale relatives.

Basilosaurus went extinct around 34 million years ago. Modern whales aren’t related to it very closely, although modern whales did share an ancestor with Basilosaurus. But Basilosaurus was a common animal and its fossils are relatively common as a result. They were so common, in fact, that they were sometimes used as house supports in parts of the American South.

In 1835 a British naturalist named Richard Harlan examined some fossils found in Alabama and decided it was a marine reptile, which he named Basilosaurus, which means king lizard. The mistake was corrected soon after when another paleontologist determined that the animal was a whale-like mammal, but it was too late to change the name due to taxonomic rules in place to minimize confusion. That’s why Basilosaurus is sometimes called Zeuglodon, since that was the name everyone wanted as a replacement for Basilosaurus.

In 1845, Albert Koch got hold of a lot of Basilosaurus fossils and decided this was his next big thing. And again, he didn’t care what Basilosaurus was or what it was called, he just wanted that moolah.

He constructed a mounted skeleton with the Basilosaurus fossils. But just as he did with his mastodon fossils, he didn’t arrange them as they appeared in life. He constructed a sea serpent that was 114 feet long, or almost 35 meters, and contained bones from six Basilosauruses, as well as some ammonite shells to bulk it out even more. He named it Hydrarchos and exhibited it first in New York City, then went on tour throughout the United States and Europe. It was even more popular than Missourium. Heck, I would have paid to see it.

Koch sold Hydrarchos to King Friedrich Wilhelm IV of Prussia, who exhibited it in the Royal Anatomical Museum in Berlin even though the paleontologists there really, really didn’t want it. Kock promptly bought more Basilosaurus bones and built a new fake, a mere 96 feet long this time, or 29 meters. He toured with it and sold it to another flim-flam artist in Chicago, who exhibited it until 1871, when the great Chicago fire destroyed it and most of the rest of Chicago.

Koch wasn’t the only person putting together real bones to make a fake animal back then, but at least he did it for the money. Other fakes were more insidious because we aren’t even sure why the hoaxer did it. That’s the case with the so-called Piltdown Man.

This is how the story goes. A man called Charles Dawson said that a worker at a gravel pit in Piltdown had given him a piece of skull in 1908. Dawson searched the pit and found more pieces, which he gave to a geologist at the British Museum, Arthur Woodward. Woodward and Dawson both returned to the gravel pit in 1912, where they found more pieces of the skull and part of a jawbone. Woodward reconstructed the skull from the pieces and reported that the ape in question must be a so-called missing link between humans and apes.

Just going to mention here that if anyone refers to a fossil as a missing link, you should be suspicious that maybe they don’t actually know what they’re talking about, or that the fossil is a fake.

Not everyone agreed with the reconstruction. In 1913, Woodward, Dawson, and a geologist and priest named Pierre Teilhard de Chardin returned to the gravel pit. Teilhard found an ape-like canine tooth that fit the jaw. But the tooth raised even more controversy, leading to the loss of friendships and colleagues splitting into camps for and against the Piltdown fossil. Teilhard de Chardin washed his hands of the whole thing and moved to France, and later helped discover Homo erectus, one of our direct ancestors.

Piltdown Man, of course, was a fake. Some people had already suspected it was a fake in 1912, and through the years afterwards people repeatedly examined the bones and kept pointing out that it was a fake. Now, of course, it’s easy for researchers to see that the jaw and teeth are from an orangutan while the skull is from a human. But for a long time, no one was sure who was behind the hoax. Was it Dawson, Woodward, Teilhard de Chardin, or all of them together? Or did someone else plant the fakes for those people to find?

In 2008, a team of experts decided to examine the fossil and the circumstances surrounding its so-called discovery. It took them eight years. They determined that the orangutan teeth were all from the same animal while the pieces of skull came from at least two different people and were possibly several hundred years old. The jaw and skull pieces had been treated with putty, paint, and stain to make them look fossilized, with some carving to make the bones match up better. The hoaxer had even crammed pebbles into the natural hollow places inside the bones, then puttied them over, presumably to make the bones weigh more and therefore feel more like fossils.

All these methods were the work of a single person, and experts have seen that person’s work before. Charles Dawson was an amateur geologist, historian, and archaeologist who “discovered” a lot of things, almost all of which have been proven to be hoaxes. But the Piltdown man hoax was the one that got him into the history books, even if only as a cheater.

So why did Dawson do it? It’s possible he wanted Britain to be home to a human ancestor more impressive than Homo heidelbergensis, which was discovered in Germany in 1907 and which was probably the common ancestor of humans and Neandertals. More likely, he just wanted to be part of the excitement of a big discovery, one which would bring him the respect of the professional scientists he envied. His other hoaxes had brought him a certain amount of fame and weren’t discovered during his lifetime, so he just kept making them.

You’d think the days of faked fossils were behind us now that paleontology is so much more sophisticated. But fake fossils are actually more of a problem now than ever, mostly because fossils can be worth so much money. Usually the fakes are obvious to experts, but sometimes they’re much more sophisticated and can fool paleontologists for at least a short time. And that brings us to Archaeoraptor.

In 1999, National Geographic announced the discovery of a feathered dinosaur fossil from China, which was a mixture of elements seen in both dinosaurs and birds. National Geographic called it a missing link between dinosaurs and birds.

Yep, another missing link.

Archaeoraptor looked like a small dinosaur but with feather impressions. This doesn’t sound weird to us now, but in 1999 it was shocking. Dinosaurs with feathers? Who ever heard of such a thing! Supposedly, the farmer who found the fossil had cemented the broken pieces together as best he could before selling it to a dealer. The fossil ended up in the United States where it was bought in early 1999 by The Dinosaur Museum in Utah for $80,000.

The National Geographic Society was interested in publishing an article about it in the magazine after the official description appeared in Nature. But Nature rejected the description. The paleontologists tried the journal Science next but again, Science rejected it. By then, other paleontologists who had examined the fossil reported that it wasn’t one fossilized animal but pieces from at least three different animals glued together to look like one. Albert Koche would be proud.

But National Geographic decided not to pull the article. It appeared in the November 1999 issue and the fossil itself was put on display at the National Geographic Society in Washington DC.

Meanwhile, a paleontologist named Xu Xing who’d seen the Archaeoraptor fossil thought it looked really familiar. He asked around in the area of China where Archaeoraptor was supposedly found, and eventually discovered the fossil of a small dinosaur called dromaeosaur. The tail of Archaeoraptor matched the tail of the Dromaeosaur fossil exactly—like exactly, right down to a yellow ochre stain in the same place. This doesn’t mean it was a fake or a copy, but that the two pieces had once been joined. Quite often fossils leave impressions on both sides of a piece of rock, which are called the slab and counterslab. Once Xing’s information got out, people started calling the fossil the Piltdown bird.

Remember last week when an extinct peccary tooth was misidentified as an ape tooth? People who didn’t believe evolution was real claimed that that one mistake proved they were right and all of science was wrong wrong wrong. Well, the same argument is going on today with people who still don’t believe evolution is real. For some reason they think that because Archaeoraptor was a hoax, evolution is somehow also a hoax—even though we now have plenty of perfectly genuine feathered dinosaur fossils that show how a branch of dinosaurs evolved into modern birds.

There are a lot of hoaxed fossils coming from China, which has some of the world’s most amazing fossil beds and some of the most amazingly well preserved fossils in the world. But because the people finding them are often desperately poor farmers, it’s common for fossils to be sold to dealers for resale. The dealers prepare the fossils and sometimes, to improve the resale value, they add details that aren’t really there to make the fossils seem more valuable. Even worse, the preparation by non-experts and those added details often destroy parts of the fossil that are then lost to science forever. And because the fossils are dug up by non-experts, paleontologists usually don’t know exactly where the fossils were found, which means they can’t properly estimate the fossil’s age and other important information.

Let’s finish with a very old hoax that was started for the best of reasons but took some unusual twists and turns. Way back in the late 17th century, the countryside near Rome in Italy kept getting flooded by rivers. Rumor had it that a dragon-like monster was responsible, that when it moved around too much in the river where it lived, the river overflowed its banks like water out of an overfull bathtub. In actuality the area is in a natural floodplain so of course it was going to flood periodically, but that didn’t make it any easier for the people who lived there.

A Dutch engineer, architect, and engraver named Cornelius Meyer had a solution, though, involving levees to make the River Tiber more navigable and less prone to flooding. He started the project around 1690 but had trouble with his local workers. They expected to come across the dragon at any moment, which made them reluctant to get too near the river.

So Meyer decided to show them that the local dragon was dead. In 1691 he “found” its remains and mounted them to put on display. The workers were satisfied and got to work building the levees that did exactly what Meyer promised, reducing flooding and saving many lives. No one knows what happened to Meyer’s dragon, but we have an engraving he made of it in 1696. You can see it in the show notes. It shows a partially skeletal monster with hind legs, bat-like wings, a long tail, and horns on its skeletal head.

Centuries later, in 1998 and again in 2006, two men saw the engraving reprinted in a book about dragons published in 1979 and decided it was a depiction of a recently killed pterosaur. Wait, what? Pterosaurs disappear from the fossil record at the same time as non-avian dinosaurs, about 66 million years ago. Why would anyone believe Meyer’s dragon was a pterosaur? It didn’t even look like one.

The two men were part of a group called the young-earth creationists, who believe the earth is only about 6,000 years old. In order to shoehorn the entire 4 ½ billion years of earth’s actual history into only 6,000 years, they claim that rocks only take a few years to form and that dinosaurs and other extinct animals either still survive today in remote areas or survived until modern times. I shouldn’t have to point out that their ideas make no sense when you understand geologic processes and other fields like cosmology, the study of the entire universe and how planets form. Young-earth creationists are always on the lookout for anything that fits their theories, like so-called living fossils and cryptids that resemble dinosaurs, like the mokele mbembe we talked about way back in episode two. I’m not sure why they think that finding a living dinosaur would prove that the earth is only 6,000 years old. All it would prove is that that a non-avian dinosaur survived the Cretaceous-Paleogene extinction event 66 million years ago.

Anyway, these two men decided that Meyer’s dragon was a pterosaur, which brought the engraving to the attention of modern scientists, who hadn’t known about it before. Obviously the dragon wasn’t actually a pterosaur. What was it?

The original remains were long gone, but the engraving was of extremely high quality. In 2013 researchers were actually able to determine what animal bones Meyer had used to make his dragon. The skull is from a dog, the jaw is from another dog, the ribs are from a large fish, the hind limbs are actually the front leg bones of a young bear, and so on. The wings, horns, and a few other parts are carvings.

Gradually, historians pieced together the real story behind Meyer’s dragon. We don’t know who actually made the fake dragon, but they did a great job. But it wasn’t a real dragon, and it definitely wasn’t a pterosaur.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. 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 131: Paleontological Mistakes

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Part of the scientific method involves making mistakes and correcting them. Here are some interesting and sometimes goofy mistakes made by paleontologists through the years, and how the mistakes were corrected.

Iguanodon did not actually look like this (left). It looked like this (right):

Pterosaur did not actually look like this (left). It looked like this (right):

Elasmosaurus did not actually look like this (left). It looked like this (right):

Apatosaurus/brontosaurus did not actually look like this (left). It looked like this (right):

Stegosaurus did not actually look like this (left). It looked like this (right):

Gastornis did not actually look like this (left). It looked like this (right):

Those are Gastornis’s footprints:

Show transcript:

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

Paleontology is the study of fossils, and really it’s only been a discipline for a little over a century. Back in the 19th and early 20th centuries, even experts made major mistakes in preparing and assembling fossil skeletons, and dishonest amateurs made deliberate errors so their fossil animals looked bigger or scarier. Many of these mistakes or hoaxes were displayed in museums, sometimes for decades.

I found so many interesting examples during my research that I decided to split the episode into two. This week we’ll learn about some paleontological mistakes and what the fossil animals really looked like when they were alive. Next week we’ll look at the frauds and hoaxes.

We’ll start with Iguanodon, a dinosaur that lived around 125 million years ago in what is now Europe. It ate plants and was fairly common, with a number of species now known to science. The biggest could grow as much as 43 feet long, or 13 meters. It had teeth that resemble an iguana’s, which is how it gets its name, and a beak probably covered in keratin that it used to clip through tough plants. It probably mostly walked on two legs and browsed from trees, but its front legs were long and it might have spent at least some of its time on all fours. But the most interesting thing about Iguanodon was its hands. Its little finger was slender and usually longer than the others and many researchers think it was used for handling food and other objects. The first finger, which is equivalent to a thumb, wasn’t so much a digit as just a big spike. It’s called a thumb spike and no one’s sure what it was for. It might have been used for defense, but it might also have been used to help dig up plants. Maybe it was used for both. But it was the source of an embarrassing mistake that many paleontologists made for years.

Iguanodon came to the attention of science in 1822 when a medical doctor in Sussex, England found some fossilized teeth. No one was sure what kind of animal the teeth belonged to, although guesses ranged from a crocodile to a rhinoceros. In 1824 the doctor, Gideon Mantell, noted the teeth’s resemblance to iguana teeth, but so big that he estimated Iguanodon must have been almost 60 feet long, or 18 meters. He also thought Iguanodon looked like an iguana.

In 1834 more Iguanodon fossils came to light in a quarry and Mantell bought them. This incomplete skeleton included a thumb spike, but Mantell didn’t know where it belonged. He thought it was a horn, so when he made a drawing of the living animal, he placed the thumb spike on the nose.

And there it stayed, despite other fossils found with the thumb spike in place on the hand, and despite other scientists pointing out that they didn’t think Iguanodon had a horn on its nose. It wasn’t until 1882 that the nose horn vanished for good and Iguanodon started looking more like itself.

Similarly, pterosaurs have been misunderstood since the very beginning, with a lot of frankly ridiculous suggestions made about them. To be fair, they are really strange animals and nothing like any animal living today. The first pterosaur was described in 1784 by an Italian naturalist, but he thought it was a swimming animal and that its wing bones were actually flippers. Zoologist Georges Cuvier pointed out it was a flying reptile in 1801, but the swimming hypothesis wasn’t abandoned for decades after that. Even after the flying part was accepted by other researchers and the general public, many people believed they were related to bats for a remarkably long time. In 1843 one scientist suggested pterosaurs were not only bats, but specifically marsupial bats. (There are no marsupial bats. Bats are placental mammals.) The notion that pterosaurs and bats were related hung around a really long time, right up to the 1930s, although experts had more or less figured it out by then.

Elasmosaurus lived around 80 million years ago and was a type of plesiosaur. We talked about Elasmosaurus in episode 92 about marine reptiles. It wasn’t a dinosaur but it lived at the same time as dinosaurs, and could grow up to 34 feet long, or over 10 meters. It had a very long neck containing 72 vertebrae, a short tail, and four paddle-like legs. These days we know that the neck wasn’t very flexible, but for a long time Elasmosaurus and its relatives were depicted with flexible, serpentine necks. But the real mistake came when it was first discovered.

The first Elasmosaurus fossil was found in Kansas in 1867 and given to Edward Cope, a well-known paleontologist who discovered many fossil species found in North America.

The problem was, Cope was the bitter rival of another well-known paleontologist, Othniel Marsh. The two men were so frantic to publish more descriptions of new animals than the other that it sometimes led to sloppy work. That may have been why, when Cope described Elasmosaurus in 1869, he placed its head at the end of its tail so that it looked like it had a short neck and a really long tail instead of the other way around. The bones were all jumbled together and the jaws had ended up at the wrong end of the skeleton when it was covered over with sediment and the fossilization process began.

Another paleontologist pointed out Cope’s mistake only a few months later. Cope tried to buy up all the copies of the article and reissued a corrected version. But Cope’s nemesis Marsh got hold of a copy of the original article and was absolutely gleeful. He never would let Cope forget his mistake, and in fact it was the final straw in the relationship between the two. Cope and Marsh had started out as friends but their friendship soured, and by 1870 they pretty much loathed each other.

But Marsh made his own mistakes. In 1877 he found a dinosaur he named Apatosaurus, although the specimen was missing a skull. He used the skull of a different dinosaur when he prepared the specimen. Then in 1885 his workers found a similar-looking skeleton with a skull. He named it Brontosaurus.

Guess what. They were the same animal. Marsh was so eager to describe a new dinosaur that Cope hadn’t described yet that he didn’t even notice. But for some reason the name Brontosaurus stuck in pop culture, which is why you probably know what a Brontosaurus was and what it looked like, while you may never have heard of Apatosaurus. The mistake has been corrected and the dinosaur’s official scientific name is Apatosaurus, but Marsh’s Apatosaurus skeleton from 1877 didn’t get the right skull until 1979. The skeleton had been on display with the wrong skull for almost a century, but researchers found the correct skull that had been unearthed in 1910 and stored away.

Apatosaurus lived in North America around 150 million years ago and was enormously long, growing on average 75 feet long from head to tail, or 23 meters. It ate plants, and some researchers suggest that it used its incredibly long tail as a whip to scare predators by cracking the whip and making a loud noise. This sounds absurd but the physiology of the tail’s end supports that it could probably withstand the pressures involved in a whip-crack. The neck was also quite long and researchers are still debating how flexible it was. The reason so much old artwork of Apatosaurus/Brontosaurus shows the animal standing in water eating swamp plants is because scientists used to think it was such a heavy animal that it couldn’t even support its own weight out of the water, much like whales. Not true, of course. It had strong, column-like leg bones that had no trouble supporting its weight on dry land, and it lived on what are referred to as fern savannas. Grass hadn’t yet evolved so the main groundcover was made up of ferns.

The name Brontosaurus has been retained for some Apatosaurus relations, fortunately, because it’s a pretty nifty name. It means thunder lizard.

Marsh is also responsible for the notion that some of the larger dinosaurs, specifically Stegosaurus, had a second brain at the base of their tails. This isn’t actually the case at all. Marsh just couldn’t figure out how such a large animal had such a small brain. Then again, Marsh also thought Stegosaurus’s tail spikes, or thagomizer, belonged on its back while its back plates belonged on its tail.

If you want to learn more about the Stegosaurus, check out episode 107 where we learn about it and Ankylosaurus. It’s too bad a paleontologist named Charles Gilmore couldn’t listen to that episode, because in 1914 he decided the back plates were osteoderms that lay flat on its skin. This was an early idea of Marsh’s that he had rejected early on but which Gilmore liked. Gilmore also thought the thagomizer spikes grew between the back plates so that the Stegosaurus was covered in both big plates like armor with spikes in between the plates.

A man named Henry Fairfield Osborn made a couple of mistakes too. He was the guy who named Oviraptor, which means “egg thief.” That was a reasonable assumption, really, since the first specimen was found in 1923 in a nest of Protoceratops eggs…but the Protoceratops eggs were later found to actually be Oviraptor eggs, and Oviraptor was just taking care of its own nest.

In 1922 Osborn was the president of the American Museum of Natural History when a rancher sent him a fossil tooth he’d found in Nebraska in 1917. Paleontologists often have to extrapolate an entire animal from a single fossil, and teeth are especially useful because they tell so much about an animal. So Osborn examined the tooth carefully and published a paper describing the ape that the tooth came from.

If you remember, though, there are no apes native to the Americas, just monkeys. The media found out about the discovery and wrote articles about the missing link between humans and apes, which was a popular topic back before people fully understood how evolution worked and when so little was known about human ancestry. The papers called the fossil ape the Nebraska man.

Then, a few years later, paleontologists went to Nebraska to find the rest of the fossilized ape bones. And while they did find them, they didn’t belong to an ape. The tooth came from a species of extinct peccary. You know, a type of pig relation. Peccaries do evidently have teeth that look a lot like human teeth, which is kind of creepy, plus the fossil tooth was badly weathered. Osborn retracted his identification in 1927.

All this wouldn’t have been a big deal except that people who didn’t believe evolution was real decided that this one relatively small mistake, quickly corrected, meant ALL scientists were ALL wrong FOREVER.

We’ll finish with a bird fossil, a bird you’ve probably never heard of although it’s massive. The first Gastornis fossil was found in the mid-19th century near Paris and described in 1855. More fossils were found soon after, and in the 1870s there were enough Gastornis bones that researchers were able to reconstruct what they thought it looked like, a gigantic crane. They were wrong.

Gastornis was as big as a big moa, over six and a half feet high, or 2 meters. It had a heavy beak and a powerful build that for over a century led many paleontologists to think it was a predator. But these days, we’re pretty sure it only ate tough plant material. Its bill could have crushed nuts but wasn’t the right shape to strip meat from bones, and a carbon isotope study of Gastornis bones indicate that its diet was entirely vegetarian.

Gastornis had vestigial wings that probably weren’t even visible under its body feathers. It was actually related most closely to modern waterfowl like ducks and geese. We have some fossilized Gastornis eggs and they were bigger than ostrich eggs, although they were shaped differently. They were oblong instead of ovoid, about ten inches long, or over 25 cm, but only four inches in diameter, or 10 cm. Only the elephant bird of Madagascar laid bigger eggs. We even have two fossil feather impressions that might be from Gastornis, and some fossil footprints in Washington state that show Gastornis had three toes with blunt claws. The bird went extinct around 40 million years ago.

At about the same time that Gastornis was being described in Europe as a kind of giant wading bird, our old friend Edward Cope found some bird fossils in New Mexico. He described the bird in 1876 as Diatryma gigantea and recognized that it was flightless. Cope’s deadly enemy Othniel Marsh also found a bird’s toe bone and described it as coming from a bird he named Barornis regens in 1894. As more and more fossils were found, however, it became clear that Cope’s and Marsh’s birds were from the same genus, so Barornis was renamed Diatryma.

By then, some paleontologists had already suggested that Diatryma and Gastornis were the same bird. In 1917 a nearly complete skeleton, including the skull, was discovered in Wyoming in the United States, but it didn’t really match up to the 1881 reconstruction of Gastornis.

But in the 1980s, researchers looked at that reconstruction more closely. It turned out that it contained a lot of mistakes. Some of the elements weren’t from birds at all but from fish and reptiles, and some of the broken fossil bones had been lengthened considerably when they were repaired with plaster. A paper published in 1992 highlighted these mistakes, and gradually the use of the term Diatryma was changed over to Gastornis.

So remember, everyone, don’t be afraid to make mistakes. That’s how you get better at things. And for the same reason, don’t make fun of other people who make mistakes. Other people get to learn stuff too. And even if you don’t think you’ve made a mistake, maybe double check to make sure you didn’t accidentally include a fish fossil in your extinct flightless bird reconstruction.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. 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 125: Triceratops and other ceratopsids

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It’s time to learn about some more dinosaurs, ceratopsids, including the well-known Triceratops!

Triceratops:

An artist’s frankly awesome rendition of Sinoceratops. I love it:

A Kosmoceratops skull:

Pachyrhinosaurus had a massive snoot:

Protoceratops:

Fighting dinos!

Show transcript:

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

Back in episode 107, about ankylosaurus and stegosaurus, I mentioned that one day I’d do an episode all about triceratops and its relations. Well, that day is today. It’s the ceratopsid episode!

Ceratopsids are a family of dinosaurs with elaborate horns on their faces and frills on the back of their heads. They almost all lived in what is now North America and most of them lived in the late Cretaceous. Triceratops is the most well known, so we’ll start with it.

The name triceratops, of course, means three face horns, and it did indeed have three face horns. It had one on its nose and two on its brow, plus a frill that projected from the back of its skull.

Triceratops was a big animal, around 10 feet high at the shoulder, or 3 meters, and about 30 feet long, or 9 meters. Its body was bulky and heavy, sort of like a rhinoceros but, you know, even bigger and more terrifying.

Like the rhinoceros, triceratops was a herbivore. It had a horny beak something like a turtle’s that it probably used to grab plant material, and it had some 40 teeth on each side of the jaw. These teeth were replaced every so often as the old ones wore down, sort of like crocodilians do. Back when triceratops lived, around 68 million years ago, grass hadn’t developed yet. There were prairies in parts of western North America the same way there are today, but instead of grass, the prairies were covered in ferns. Many researchers think triceratops mostly ate ferns, grazing on them the same way bison graze on grass today.

In fact, the first paleontologist to study a triceratops fossil thought it was an extinct type of bison. This was a man called Othniel Charles Marsh. To his credit, Marsh only had a little piece of a triceratops skull to examine, the piece with the brow horns. And since the brow horns of a triceratops do look a little like the horn cores of a bovid, and since this was 1887 before a lot was known about dinosaurs, and since the fossil was found in Colorado where the buffalo roam, it’s understandable that Marsh would have assumed he was looking at a gigantic fossil bison skull. He figured it out the following year after examining another skull with the nose horn intact, since bovids are not known for their nose horns, and he naturally named it Triceratops.

It’s tempting to assume that Triceratops was a herd animal, but we don’t have any evidence that it lived in groups. It was common and we have lots of fossil triceratops, especially the thick-boned skulls, but it seems to have mostly been a solitary animal.

It’s pretty obvious that the triceratops’ horns must have been for defense. It lived at the same time as Tyrannosaurus rex, which preyed on triceratops often enough that we have a lot of Triceratops fossils with T rex tooth marks in the bones. We also have some triceratops fossils with T rex tooth marks in the bones that show signs of healing, indicating that the triceratops successfully fended off the T rex and lived. But what was the frill for?

Researchers have been trying to figure this out for years. There were a lot of different ceratopsid species, many of which may have overlapped in range and lived at the same time, so some researchers suggest the frill’s size and shape may have helped individuals find mates of the same species. Triceratops has a rather plain frill compared to many ceratopsid species, which had frills decorated with points, spikes, scalloped edges, lobes, and other ornaments.

But the ornamental elements of the frills change rapidly through the generations, which suggests that they weren’t for species recognition. If that was the case, the frills would have stayed about the same to minimize confusion. Instead, they get more and more elaborate, which suggests that they were a way to attract mates who liked fancy head frills. You know, like a snazzy hairstyle.

Of course, the frill could have more than one use. It could be attractive to potential mates and also could have protected the back of the skull from T rex bites, just like a snazzy hairstyle still keeps your head warm in cold weather. Then again, in many species of ceratopsid the frill is thin and rather fragile, so it’s more likely to be just for display. It’s very likely that the frills were brightly colored or patterned.

So what were some of these other ceratopsids with strange shaped frills? I’m SO glad you asked! There were so many ceratopsids, and they all had bodies shaped roughly the same but with head frills and horns that looked very different from each other. Some had no horns, just a frill. Some just had a nose horn, some just had brow horns. The horns were shaped differently in different species, too. Researchers group ceratopsids into two major groups: the chasmosaurines, which have longer frills and usually long brow horns and short nose horns; and the centrosaurines, which typically had larger nose horns and small brow horns, and snouts that were thicker top to bottom.

Almost all the ceratopsids have been found in North America, where they were super common in the Cretaceous. But Sinoceratops was discovered in 2008 in China. It wasn’t as big as Triceratops, topping out at about 6 ½ feet tall, or 2 meters, but what it lacked in bulk it made up in head frill ornamentation. Its frill was relatively short and was edged with small horns that curve forward. Its frill also had knobs along its edge and down the middle, which is unique among all ceratopsids and may have been the base for small keratin horns. Since keratin doesn’t fossilize, we have no way of knowing. It also had two holes in the frill that made it lighter, but they would have been covered with skin (no matter what a certain movie may have led you to believe). Its single nose horn pointed almost straight up, and in front of the nose horn it had a bony knob. It basically had no brow horns, just what may have been bony knobs above its eyes.

Kosmoceratops had probably the most ornamented skull of any known ceratopsid, and maybe any known dinosaur, with 15 horns growing from it. The rear of its frill curled forward like a collar, edged with flat, pointed projections. The frill was scalloped along its sides. Its brow horns were long, pointy, and arched sideways and slightly downward. Kosmoceratops also had a cheek horn under each eye and a flattened nose horn just in front of the brow horns. It lived in what is now Utah, in the United States, some 76 million years ago, and was only described in 2010.

Pachyrhinosaurus had flattened bony nose and brow horns more properly called bosses, since they aren’t actually horns. But Pachyrhinosaurus did have horns on its frill, although the size, shape, and number of the frill horns vary from individual to individual.

These bosses resemble the base of rhinoceros horns, which as you may recall are made of keratin. Some researchers think the bosses found in Pachyrhinosaurus and other ceratopsids may have also had keratin horns growing from them.

Remember how I said Triceratops didn’t appear to be a herd animal? Triceratops is considered a chasmosaurine, and chasmosaurines all seemed to be fairly solitary animals. But the other big group of ceratopsids, centrosaurines, may have been herd animals. Pachyrhinosaurus was a centrosaurine, for instance, and several bonebeds containing dense collections of fossil pachyrhinosaurus have been found where the individuals appear to have died at the same time. The biggest found so far is in Alberta, Canada, where paleontologists have excavated thousands of bones, from full grown adults to babies. Researchers suggest a herd of the animals may have died trying to cross a flooded river. The species of Pachyrhinosaurus found in the Alberta bonebed had both bosses and short brow horns.

Even though only one species of ceratopsid has been discovered in Asia so far, earlier basal forms were common in Asia. Protoceratops, which only stood about two feet tall, or 60 cm, lived in what is now the Gobi Desert in Mongolia around 80 million years ago. Researchers think some of these early species in the genus Protoceratops migrated into North America on the Bering land bridge, where they evolved into ceratopsids.

Protoceratops looked like a mini ceratopsid with a simple neck frill and no horns. We have a lot of Protoceratops fossils and some of them are frankly amazing.

For instance, a Protoceratops fossil found in 1965 was preserved with its own footprint in the ground near it. The fossils of baby protoceratopses have been found together in one nest, which suggests the parents cared for their young. We even have a fossil of a protoceratops and a Velociraptor that both died together while fighting. The velociraptor’s hind leg is extended where it kicked protoceratops with its vicious claws, but the velociraptor’s arm is in protoceratops’s jaws, broken.

Fighting dinosaurs. It’s one of those things that makes life worth living, you know?

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 124: Updates 2 and a new human

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It’s our second updates and corrections episode! Thanks to everyone who sent in corrections and suggestions for this one! It’s not as comprehensive as I’d have liked, but there’s lots of interesting stuff in here. Stick around to the end to learn about a new species of human recently discovered on the island of Luzon.

The triple-hybrid warbler:

Further reading:

New species of ancient human discovered in the Philippines: Homo luzonensis

Show transcript:

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

Yes, it’s our second updates episode, but don’t worry, it won’t be boring!

First, a few corrections. In episode 45 I talked about monotreme, marsupial, and placental mammals, and Tara points out that the placenta and bag of waters are different things. I got them mixed up in the episode. The bag of waters is also called the amniotic sac, which protects and cushions the growing baby inside with special amniotic fluid. The placenta is an organ attached to the lining of the womb, with the bag of waters inside the placenta. The umbilical cord connects the baby to the placenta, which supplies it with all its needs, including oxygen since obviously it can’t breathe yet.

Next, I covered this correction in in episode 111 too, but Judith points out that the picture I had in episode 93 of the Queen Alexandra’s birdwing butterfly was actually of an atlas moth. I’ve corrected the picture and if you want to learn more about the atlas moth, you can listen to episode 111.

Next, Pranav pointed out that in the last updates episode I said that the only bears from Africa went extinct around 3 million years ago–but the Atlas bear survived in Africa until the late 19th century. The Atlas bear was a subspecies of brown bear that lived in the Atlas Mountains in northern Africa, and I totally can’t believe I missed that when I was researching the nandi bear last year!

Finally, ever since episode 66 people have been emailing me about Tyrannosaurus rex, specifically my claim that it was the biggest land carnivore ever. I don’t remember where I found that information but it may or may not be the case, depending on how you’re defining biggest. Biggest could mean heaviest, tallest, longest, or some combination of features pertaining to size.

Then again, in 1991 a T rex was discovered in Canada, but it was so big and heavy and in such hard stone that it took decades to excavate and prepare so that it can be studied. And it turns out to be the biggest T rex ever found. It’s also a remarkably complete fossil, with over 70% of its skeleton remaining.

The T rex is nicknamed Scotty and was discovered in Saskatchewan. It lived about 68 million years ago, and turns out to not only be the biggest T rex found so far, it was probably the oldest. Paleontologists estimate it was over 30 years old when it died. It was 43 feet long, or 13 meters. This makes it bigger than the previously largest T rex found, Sue, who was 40 feet long, or 12.3 meters. Scotty also appears to be the heaviest of all the T rexes found, although estimates of its weight vary a lot. Of course some researchers debate Scotty’s size, since obviously it’s impossible to really know how big or heavy a living dinosaur was by just looking at its fossils. But Scotty was definitely at least a little bigger than Sue.

Scotty is on display at the Royal Saskatchewan Museum in Canada.

Way back in episode 12, I talked about snakes that were supposed to make noises of one kind or another. Many snakes do make sounds, but overall they’re usually very quiet animals. A snake called the bushmaster viper that lives in parts of Central America has long been rumored to sing like a bird. The bushmaster can grow up to ten feet long, or 3 meters, and its venom can be deadly to humans.

Recently, researchers discovered the source of the bushmaster’s supposed song. It’s not a snake singing. It’s not a bird singing. It’s not even a single animal–it’s two, both of them tree frogs. One of the frogs is new to science, the other is a little-known frog related to the new one.

I tried so hard to find audio of this frog, and I’m very bitter to report that I had no luck. The closest I could find was not great audio of this frog, whose name I forgot to write down, which I think is related to the new frogs.

[frog sound]

Now let’s do some quick, short updates, mostly from recent articles I’ve happened across while researching other things.

A triple-hybrid warbler, its mother a golden-winged/blue-winged hybrid (also called a Brewster’s warbler) and its father a warbler from a different genus, chestnut-sided, was sighted in May of 2018 by a birder in Pennsylvania. Lowell Burket noticed it had characteristics of both a blue-winged and a golden-winged warbler but sang like a chestnut-sided warbler. He contacted the Cornell Evolutionary Biology Lab about the bird with photos and video of it, and they sent a researcher, David Toews, out to look at it. Toews caught the bird, measured it, and took a blood sample for analysis. I think a listener told me about this article but I didn’t write down who, so thank you, mystery person.

Red-fronted lemurs chew on certain types of millipedes and rub the chewed-up millipedes on their tails and their butts. They also eat some of the millipedes. Researchers think the millipedes secrete a substance called benzoquinone, which acts as an insect repellant and may also help the lemurs get rid of intestinal parasites. Other animals rub crushed millipedes on their bodies for the same reasons.

A recent study of saber-toothed cat fossils show that many of the animals with injuries to their jaws and teeth that would have kept them from hunting properly survived on softer foods like meat and fat. Researchers think the injured cats were provided with food by other cats, which suggests they were social animals. The study examined micro-abrasions on the cats’ teeth that give researchers clues about what kinds of food the animals ate.

Simon sent me an article about a 228 million year old fossil turtle, Eorhynchochelys [ay-oh-rink-ah-keel-us]. It was definitely a turtle but it didn’t have a shell. Instead, its ribs were wide, which gave its body a turtle-like shape. Turtle shells actually evolved from widened ribs like these. Researchers are especially interested because Eorhynchochelys had a beak like modern turtles, while the other ancient turtle we know of had a partial shell but no beak. This gives researchers a better idea of how turtles evolved. Oh, and in case you were wondering, Eorhynchochelys grew over six feet long, or over 1.8 meters.

The elephant bird, featured in episode 51, was a giant flightless bird that lived in Madagascar. Recently new research about elephant birds has revealed some interesting information. For one thing, we now know what the biggest bird that ever lived was. It’s called Vorombe titan and grew nearly ten feet tall, or 3 meters, and weighed up to 1,800 lbs, or 800 kg. It was first discovered in 1894 but not recognized as its own species until 2018.

There’s also some evidence that at least some elephant bird species may have been nocturnal with extremely poor vision. This is the case with the kiwi bird, which is related to the elephant bird. Brain reconstruction studies of two species of elephant bird reveal that the part of its brain that processed vision was very small. It resembles the kiwi’s brain, in fact. One of the species studied had a larger area of the brain that processed smell, which researchers hypothesize may mean it lived in forested areas.

Another study of the elephant bird bones show evidence that the birds were killed and eaten by humans. But the bones date to more than 10,000 years ago. Humans supposedly didn’t live in Madagascar until 4,000 years ago at the earliest. So not only is there now evidence that people colonized the island 6,000 years earlier than previously thought, researchers now want to find out why elephant birds and humans coexisted on the island for some 9,000 years before the elephant bird went extinct. Hopefully archaeologists can uncover more information about the earliest people to arrive on Madagascar, which may help us learn more about how they interacted with the elephant bird and other extinct animals of the island.

Speaking of humans, humans evolved in Africa and until very recently, evolutionarily speaking, that’s where we all lived. Scientists rely on fossils, archaeological materials, and studies of ancient DNA to determine when and where humans spread beyond Africa. But at the moment, the DNA that researchers have studied doesn’t overlap entirely with what we’ve learned from the other sources. Basically this means that there are big chunks of data we still need to find to get a better picture of where our ancestors traveled. Part of the problem is that DNA preserves best in cold, dry areas, so most of the viable DNA recovered is from middle Eurasia. Fortunately, DNA technology is becoming more and more refined every year.

This brings us to a suggestion by Nicholas, who told me about a newly discovered hominin called Homo luzonensis. Homo luzonensis lived on an island called Luzon in the Philippines at least 50,000 years ago. It wasn’t a direct ancestor to Homo sapiens but was one of our cousins, although we don’t know yet how closely related.

No one thought humans could reach the island of Luzon until relatively recent times, because of how remote it is and because it hadn’t been connected to the mainland for the last 2 ½ million years. But when Homo floresiensis was discovered in 2004 on the island of Flores in Indonesia, which you may remember from episode 26, suddenly scientists got interested in other islands. Researchers knew there had been human settlements on Luzon 25,000 years ago, but no one had bothered to search for older settlements. In 2007 a team of paleoanthropologists returned to the island and found a foot bone that looked human. In 2011 and 2015 the team found some teeth and more bones from at least three different individuals.

We don’t know a whole lot about the Luzon humans yet. The discoveries are still too new. The Luzon hominins have a combination of features that are unique, a mixture of traits that appear more modern and traits that are seen in more ancient hominins. They’re also smaller in stature than modern humans, closer to the size of the Flores people. Homo luzonensis apparently used stone tools since researchers have found animal bones that show cut marks from butchering.

Researchers are starting to put together a picture of South Asia in ancient times, 50,000 years ago and more, and it’s becoming clear that there were a surprising number of hominins in the area. It’s also becoming clear that hominins lived in the area a lot longer ago than we thought. Researchers have found stone tools on the island of Sulawesi that date back at least 118,000 years. Even on Luzon, in 2018 researchers found stone tools and rhinoceros bones with butcher marks that date back over 700,000 years ago. We don’t know who those people were or if they were the ancestors of the Luzon people. We just know that they liked to eat rhino meat, which is one data point.

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 122: Strange Shark Ancestors

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This week let’s learn about some ancestors of sharks and shark relatives that looked very strange compared to most sharks today!

Stethacanthus fossil and what the living fish might have looked like:

Two Falcatus fossils, female above, male below with his dorsal spine visible:

Xenacanthus looked more like an eel than a shark:

Ptychodus was really big, but not as big as the things that ate it:

A Helicoprion tooth whorl and what a living Helicoprion might have looked like:

Show transcript:

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

This week we’re going back in time again to learn about some animals that are long-extinct…but they’re not land animals. Yes, it’s a weird fish episode, but this one is about shark relatives!

The first shark ancestor is found in the fossil record around 420 million years ago, although since all we have are scales, we don’t know exactly what those fish looked like. The first true shark was called Cladoselache [clay-dough-sell-a-kee] and lived around 370 million years ago, at the same time as dunkleosteus and other massive armored fish. We covered dunkleosteus and other placoderms back in episode 33. Cladoselache grew up to four feet long, or 1.2 meters, and was a fast swimmer. We know Cladoselache ate fish because we have some fossils of Cladoselache with fish fossils in the digestive system—whole fish fossils, which suggests that cladoselache swallowed its prey whole. Cladoselache also had fin spines in front of its dorsal fins that made the fins stronger, but unlike its descendants, it didn’t have denticles in its skin. It didn’t have scales at all.

The denticles in shark skin aren’t just protection for the shark, they also strengthen the skin to allow for the attachment of stronger muscles. That’s why sharks are such fast swimmers.

[Jaws theme]

Stethacanthidae was a family of fish that went extinct around 300 million years ago. It was related to ratfish and their relatives, including sharks. Stethacanthus is the most well-known of the stethacanthidae. It grew a little over 2 feet long, or 70 cm, and was probably a bottom-dwelling fish that lived in shallow waters. It ate crustaceans, small fish, cephalopods, and other small animals.

We have some good fossils of various species of Stethacanthidae and they show one feature that didn’t get passed down to modern ratfish or sharks. That’s the shape of its first dorsal fin, the one that in shark movies cuts through the water just before something awful happens.

[Jaws theme again]

Stethacanthidae’s dorsal fin was really weird. It was shaped sort of like a scrub brush on a pedestal, with the bristles sticking upwards, which is sometimes referred to as a spine-brush complex. Researchers aren’t sure why its fin was shaped in such a way, but since it appears that only males had the oddly shaped fin, it was probably for display. It also had a patch of the same kind of short bristly denticles on its head. Males also had a long spine that grew from each pectoral fin that was probably also for display. Some researchers think the males fought each other by pushing head to head, possibly helped by the odd-shaped dorsal fin.

In the past, before researchers figured out that only the males had the strange dorsal fin, some people suggested that the fish may have used the fin as a sucker pad to attach to other, larger fish and hitch a ride. This is what remoras do. Remoras have a modified dorsal fin that is oval-shaped and acts like a sucker. The oval contains flexible membranes that the remora can raise or lower to create suction. The remora attaches to a larger animal like a shark, a whale, or a turtle and lets the animal carry it around. In return, the remora eats parasites from the host animal’s skin. But remoras aren’t related to sharks.

Other shark relatives had dorsal spines. Falcatus falcatus lived about the same time as Stethacanthus, around 325 million years ago. It grew up to a foot long, or 30 cm, and ate shrimp, fish, and other small animals. We have so many fossils of falcatus from the Bear Gulch Limestone deposits in Montana that we know quite a bit about it. It probably detected prey with electroreceptors on its snout like many modern sharks do, and it was probably a fast swimmer that could dive deeply. Its eyes are unusually large for a shark too. Females would have looked like a small, slender sharklike fish, but males had a spine that grew forward from just behind its head, sort of like a single bull’s horn. It’s called a dorsal spine and is actually a modified dorsal fin. It was probably for display, although males may have also used it to fight each other. We have a well preserved fossil of a pair of falcatus together, a male and female, where it looks like the female may be biting the male’s dorsal spine. Some researchers suggest the spine was used in a pre-mating ritual, but it’s probable that the fish just happened to die next to each other and no one was actually biting anyone.

Another shark relative with a dorsal spine is Hybodus, which grew up to 6 ½ feet long, or 2 meters. Hybodus was a successful genus of cartilaginous fish that lived from around 260 million years ago up to 66 million years ago. Researchers think its dorsal spine was used for defense since both males and females had the spine. Hybodus would have looked like a shark but its mouth was relatively small. It probably ate small fish and squid, catching them with the sharp teeth in the front of its mouth, but it also probably ate a lot of crustaceans and shellfish, which it crushed with the flatter teeth in the rear of its mouth.

Xenacanthus had a dorsal spine too, but it was a much different shark ancestor from the ones we’ve talked about so far. It lived until about 208 million years ago in fresh water. It grew to about three feet long, or one meter, and would have looked more like an eel than a shark. It was slender with an elongated body, and its dorsal fin was short but extended along the back down to the pointed tail. This suggests it probably swam like an eel, since eels have a similar fin structure. It probably ate crustaceans and other small animals.

Xenacanthus’s spine grew from the back of the skull and, unusually for a shark relation, it was made of bone instead of cartilage. Both males and females had the spine and some researchers suggest that it may have been venomous like a sting ray’s tail spine.

Rays are closely related to sharks, and if you want to see a fish that makes every single weird extinct shark look normal, just look at a sawfish. The sawfish is a type of ray and it’s alive today, although it’s endangered. I’m going to do a whole episode on rays pretty soon so I won’t go into detail, but the sawfish isn’t the only fish alive today with a long snout with teeth that stick out on either side. The sawshark is related to the sawfish but is actually a shark, not a ray. And there’s a third type of fish with a saw, related to both sawfish and sawsharks, called the Sclerorhynchidae. Sclerorhynchids went extinct around 55 million years ago and are considered part of the ray family, although they’re not ancestors of living rays. Sclerorhynchids grew around three feet long, or about a meter, and probably looked a lot like modern sawfish although with a rostrum, or snout, that was more pointed and less broad than most sawfish rostrums. The teeth that stuck out to either side were also relatively small. Researchers think Sclerorhynchids used their saws the same way modern sawfish and sawsharks do, to find small animals living on or near the bottom in shallow water and slash them to death before eating the pieces.

[Jaws theme again]

Most of the shark relatives we’ve talked about so far were pretty small, certainly compared to sharks like the great white or megalodon, which by the way we covered in episode 15 along with the hammerhead shark. But a shark called Ptychodus grew up to 33 feet long, or ten meters. It went extinct about 85 million years ago. Its dorsal fin had serrated spines and its mouth had lots and lots of really big teeth–up to 550 teeth, but they weren’t sharp. Instead, they were flattened with riblike folds that helped Ptychodus crush the mollusks it ate. It probably also ate squid and crustaceans, along with any carrion it might come across. It lived at the bottom of the ocean, but in relatively shallow areas where there were plenty of mollusks but not too many mosasaurs or other sharks that might treat Ptychodus as a nice big meal.

In episode 33, the one about dunkleosteus, we also talked about helicoprion and some of its relations. Helicoprion looked like a shark but was actually less closely related to true sharks than to ratfish. Helicoprion lived until about 250 million years ago and some researchers estimate it could grow up to 24 feet long, or 7.5 meters.

Instead of a weird dorsal fin, helicoprion had weird teeth. Weird, weird teeth. It had a tooth whorl instead of the regular arrangement of teeth, where its teeth grew in a spiral that seems to have been situated in the lower jaw. It looked like the blade of a circular saw. Now, this is bizarre but it’s not really all that much more bizarre than sawfish teeth, which aren’t even inside the mouth and stick out sideways. But the frustrating thing for researchers is that we still don’t have any helicoprion fossils except for the teeth whorls and part of one skull. Like most sharks and shark relatives, almost all of helicoprion’s skeleton was made of cartilage, not bone, and cartilage doesn’t fossilize very well. So even though helicoprion was widespread and even survived the Permian-Triassic extinction event, we don’t know what it looked like or what it ate or how exactly its tooth whorl worked. But I think it’s safe to say that it would not be good to be bitten by helicoprion.

[stop playing the Jaws theme omg]

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!

[Jaws theme again]

Episode 119: Before the Dinosaurs

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What kinds of animals lived before dinosaurs evolved? What did they evolve into? Let’s find out!

Dimetrodon! Not a dinosaur! Not even actually a reptile:

Cotylorhynchus had a teeny head. I am not even exaggerating:

Moschops had a big thick skull:

Lisowicia was the size of an elephant but looked like…well, not like an elephant:

Show transcript:

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

Lots of people know about dinosaurs. Dinosaurs are really interesting. But do you know what animals lived before dinosaurs evolved? Let’s find out.

If you’ve heard of dimetrodon, you may think it’s just another dinosaur. It’s the animal that looks sort of like a huge lizard with a sail-like frill down its back. But not only was dimetrodon not a dinosaur, it went extinct 40 million years before the first dinosaur evolved.

Dimetrodon lived almost 300 million years ago and was a synapsid. Synapsid is a catchall term for a group of animals with both reptilian and mammalian characteristics, also sometimes called proto-mammals. The term synapsid also includes mammals, so yes, you are related to dimetrodon verrrrrrry distantly. You are more closely related to dimetrodon than you are to any dinosaur, let’s put it that way.  Dimetrodon was an early synapsid, which are referred to as pelycosaurs.

The largest species of dimetrodon grew up to 15 feet long, or 4.6 meters, with some probably growing even larger. It had serrated teeth, a long tail, short legs, and a massive sail on its back. The sail is formed from neural spines, which are basically just really long prongs of bone growing from the vertebrae. The spines were connected with webbing, although possibly not all the way to the tip of the spines. Ever since the first fossil remains of dimetrodon were discovered in 1878, scientists have been trying to figure out what the sail was for.

For a long time the most popular theory was that the sail helped with thermoregulation. That is, it helped dimetrodon stay warm in cool weather and cool in warm weather by absorbing sunshine or releasing heat, depending on where dimetrodon was. If dimetrodon was chilly, it would angle its body so that lots of sunlight reached its sail, but if dimetrodon was hot, it would find a patch of shade or turn its body so that minimal sunlight reached its sail, allowing the blood vessels covering the sail to release heat into the atmosphere.

This is a pretty good guess, since many modern animals use something similar to help regulate body temperature. That’s why African elephants have such large ears. But more recent studies of dimetrodon’s sail show that it didn’t have a lot of blood vessels, as it would if it was for thermoregulation. These days paleontologists suggest the sails may have mostly been for display. Different species had differently shaped sails, and there’s some evidence that male and female dimetrodons of the same species may have had differently shaped sails too. It’s possible the sails were brightly colored or patterned during the breeding season.

But dimetrodon wasn’t the only early synapsid with a sail. Secodontosaurus had one too and resembled dimetrodon in many ways, including having a long tail and short legs. But where dimetrodon was chunky with a massive skull, secodontosaurus was much more slender with long, narrow jaws. It may have eaten fish. It probably grew up to nine feet long, or 2.7 meters, and it lived around 275 million years ago. It was related to dimetrodon, but paleontologists aren’t sure how closely it was related.

The largest pelycosaur, or early synapsid, was cotylorhynchus [ko-tillo-rinkus], which lived around 275 million years ago in what is now North America. It was a weird-looking animal. Weird, weird weird. Seriously, it was very strange. It grew to almost twenty feet long, or 6 meters, with a barrel-shaped body, great big legs, and a long tail. But its neck was very short and its head was tiny.

Some researchers think cotylorhynchus lived in the water. Its forefeet may have been paddle-shaped. It ate plants, which is why its body was so big, since it needed room to hold lots of plants while they digested. It may have dug for roots as well, since its forefeet had long claws. Weird as it was, if you think of it as shaped sort of like a giant tortoise, its small head and big body make more sense.

Dimetrodon and other pelycosaurs lived in the early Permian era. By the mid-Permian, a group of synapsids called therapsids started evolving to become more mammal-like. The legs of therapsids were positioned more beneath the body instead of sprouting out from the sides, which is the difference between a dog’s body and a lizard’s body. This allowed therapsids to run more efficiently and breathe more efficiently when moving fast.

We know that at least some of these early therapsids had fur because paleontologists have found coprolites, which as you recall are fossilized poops, with fur embedded in them. Since this was long before mammals evolved, it had to be therapsids with fur. In fact, it was the therapsids that eventually evolved into mammals, so technically you are also a therapsid.

Therapsids were probably warm-blooded and probably had whiskers. But they wouldn’t have looked like mammals today. They probably resembled reptiles in a lot of ways, especially early therapsids. The tails of many therapsids would have looked like reptile tails, long, thick, and pointed. The heads would have looked much more like a lizard head than a mammal head, with no external ears.

Some therapsids would have looked really weird. For instance, moschops [mo-shops], which lived around 260 million years ago in what is now southern Africa. Moschops was a type of therapsid that ate plants, and it was massively built. It was around 8 feet long, or 2.5 meters, and had a thick skull and short snout with strong jaw muscles. The back sloped downward from the shoulders to a short tail. Its relatively short legs were sturdy to hold up the weight of the broad and massive body. The front legs were much farther apart than the hind legs. Its teeth were strong but not sharp; instead, they had chisel-like edges that helped it bite through tough vegetation.

Moschops had such a thick skull that many researchers think it fought other moschopses by butting heads. The small brain was extremely well protected by a skull that was as much as 6 inches thick, or 15 cm, and new research shows that the head was usually held forward instead of up. This makes sense in a grazing animal, and would also make sense if males were butting heads to impress potential mates, or if individuals fought over territory or food. If moschops did butt heads, it’s possible that it lived in groups with a certain amount of social organization.

Toward the end of the Permian, a group of therapsids called dicynodonts became widespread and lived well into the Triassic era. Dicynodonts were probably warm-blooded, probably had fur or hair, and some may have had feet that were more paw-like than reptilian, with fleshy pads. But while all these features are mammalian, most dicynodonts had a horny beak like a turtle and either no teeth at all, or only a pair of teeth in the front of the jaw that grew like tusks. Some paleontologists think only males had these tusks. Most dicynodonts were herbivorous and some dug burrows.

About 250 million years ago, there was a mass extinction event called the Permian-Triassic extinction, or sometimes just the Great Dying. Researchers aren’t sure what caused it, but like the later extinction that ended the dinosaurs, it may have been caused initially by a massive meteor impact that sent the earth’s climate into a tailspin. 96% of all marine species went extinct and 70% of land animals. This was the event that led to the rise of the dinosaurs ultimately. But some therapsids survived.

The biggest dicynodont evolved after the great dying and it was the size of an elephant. Lisowicia lived in what is now Poland around 230 million years ago, but it was probably more widespread than that sounds. We only have a single specimen of lisowicia that was discovered in south Poland in 2008. It probably stood 8 ½ feet high, or 2.6 meters. All four of its legs were positioned under the body like modern mammals, whereas most dicynodonts were similar to moschops, where the hind legs were under the body and the forelegs were more widely spaced and sprawling. But it probably didn’t look much like a modern mammal beyond that. Its head would probably have looked quite reptilian since it had a horny beak like other dicynodonts. Its tail was short.

Dicynodonts went extinct by the late Triassic, but the related cynodonts persisted. Cynodonts are the direct ancestors of mammals. You are definitely also considered a cynodont. The first cynodonts evolved in the late Permian and had a lot of traits that are still retained by mammals, such as fur, whiskers, warm-bloodedness, and teeth that are differentiated into different types like molars and incisors. They also developed what’s called a secondary palate, or as we call it, the roof of the mouth. All mammals still have this feature, which allows us to breathe and chew at the same time. But cynodonts also still probably laid eggs. Eventually cynodonts developed into monotremes like the platypus and echidna, which many researchers consider to retain many cynodont features.

Probably the largest cynodont was cynognathus, which lived around 240 million years ago. Cynognathus was a predator that grew almost four feet long, or 1.2 meters, not counting its long tail. It was widespread throughout the southern hemisphere, with cynognathus fossils of various species found in modern-day southern Africa, South America, and Antarctica. It had already evolved the secondary palate, and its head and jaws were both long and wide, with sharp teeth.

Because cynodonts lived alongside dinosaurs for millions of years, they evolved into animals that were generally quite small, no larger than a rat, and frequently nocturnal. But they were still incredibly successful, spreading out across the world and evolving into animals that looked more and more like mammals that we’d recognize today. The haramiyids were probably insectivores and lived in trees, with some species able to glide like flying squirrels or the colugo. Many cynodonts lived in large shared burrows, suggesting increasingly complex social behavior.

But not all early mammals were tiny and ran away from dinosaurs. Repenomamus [re-penno-may-mus] lived around 125 million years ago and grew over three feet long, or 1 meter. In shape, it somewhat resembled a badger with a long tail. We know it ate small animals, including hatchling dinosaurs, because fossil remains of a baby psittacosaurus [sit-acko-saurus] was found in the stomach area of a fossil repenomamus. The psittacosaurus remains were in chunks, which suggests that repenomamus had bitten it into pieces to swallow it.

Repenomamus was considered a Eutriconodont, a type of early mammal, but the eutriconodonts went extinct at about the same time as the dinosaurs.

But by then, the therapsids were fully evolved into what we have termed mammals. And they were poised to take over. Or, I should say, we mammals were poised to take over. And we have.

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 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!