Episode 131: Paleontological Mistakes

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 092: Marine Reptiles

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

A marine iguana, eatin:

Another marine iguana, swimmin:

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

A mosasaurus skeleton:

A plesiosaur skeleton:


Show transcript:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Thanks for listening!