Episode 173: The Mystery of the Forest Raven

We have a fun mystery bird this week, the forest raven! Was it a real bird??? (hint: yes, but not a raven)

The “forest raven” illustration from Swiss naturalist Conrad Gessner’s Historiae Animalium, published in 1555:

Scans of the original pages about the forest raven. It’s written in Latin:

The Northern bald ibis. Wacky hair!

Flying bald ibises:

Further viewing:

This Weird Bird May Have Been the First Protected Species

Show transcript:

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

It’s high time we had a mystery animal episode, so this week we’re going to learn about a mystery bird, one with a satisfying conclusion.

The story starts almost 470 years ago, when a scholar and physician named Conrad Gessner, who lived in Switzerland, published a book called Historia animalium. The book wasn’t like the medieval bestiaries of previous centuries, in which fantastical and real animals were listed together and half the information consisted of local superstitions. Gessner was an early naturalist, a scientist long before the term was in general use. Historia animalium consisted of five volumes with a total of more than 4,500 pages, and in it Gessner attempted to describe every single animal in the world, drawing from classical sources such as Pliny the Elder and Aristotle as well as his own observations and study.

The book contained animals that had only recently been discovered by Europeans at the time, including animals from the Americas and the East Indies. It also included a few entries which no one today believes ever existed, like the fish-like sea monk and sea bishop. Those and similar monsters were probably added by Gessner’s publishers against his will or maybe just without him knowing, since he was seriously ill by the time the volume on fish was published. For the most part, the book was as scholarly as was possible in the mid-16th century and was lavishly illustrated too.

Volume three, about birds, was published in 1555, and it included an entry for a bird Gessner called the waldrapp, or forest raven. But the illustration didn’t look anything like a raven. The bird has a relatively long neck, a crest of feathers on the back of its head, and a really long bill that ends in a little hook. Gessner wrote that the bird was found in Switzerland and was good to eat.

In fact, I spent an entire morning finding the original scanned pages of a copy of the forest raven entry, typing them as well as I could and modernizing the spelling where I knew how, and using Google translate from Latin to English. The results were…not entirely coherent. Then, after I’d done all that, I continued my research, and that included watching a short BBC film about the bird–which included part of the translation! So I transcribed it. Here’s a translation cobbled together from the BBC’s translation and other parts of the passage that me and Google translate could figure out:

“The bird is generally called by our people the Waldrapp, or forest raven, because it lives in uninhabited woods where it nests in high cliffs or old ruined towers in castles. Men sometimes rob the nests by hanging from ropes. It acquires a bald head in its age. It is the size of a hen, quite black from a distance, but if you look at it close, especially in the sun, you will consider it mixed with green. The Swiss forest raven has the body of a crane, long legs, and a thick red bill, slightly curved and six inches long. Its legs and feet are longer than those of a chicken. Its tail is short, it has long feathers at the back of its head, and the bill is red. The bill is suited for poking in the ground to extract worms and beetles which hide themselves in such places. It flies very high and lays two or three eggs. The young ones are also praised as an article of food and are considered a great delicacy, for they have lovely flesh and soft bones. Those who rob the nests of young take care to leave one chick so the parents will return the following year.”

All that sounds like a perfectly ordinary bird, although not a raven. But what was it? That’s the problem. No one knew, and eventually scholars decided that Gessner must have included a bird that didn’t exist.

But it did sound like one particular bird, just not one related in any way to the raven and not one that lived in Switzerland or other parts of Europe. That’s the northern bald ibis, which was once common across the Middle East and northern Africa.

Here’s a description of the Northern bald ibis. Let’s see how it matches up with Gessner’s forest raven.

The Northern bald ibis is a fairly large bird, about a foot long, or 31 cm, with a wingspan of four and a half feet, or 135 cm. That’s about the size of a goose. It has black feathers that shine with iridescent colors in sunlight, including bronze, violet, and green. It has long, dull red legs and a long, curved bill that’s also reddish. Its head is the same shade of dull red and has no feathers, but it does have a crest of long feathers on the back of its head and neck. It nests on cliff ledges and prefers to hunt for food in areas where the grass or other vegetation is short, such as pastures, fallow fields, semi-arid steppes, and golf courses, often ten miles or more from the cliffs where it nests, or 15 km. It eats insects and other small invertebrates, but it especially likes lizards and beetles. It probes into soft, sandy soil with its bill to find most of its food. The birds live in small flocks and often fly in a V formation.

The northern bald ibis mates for life. The male finds a good nesting site and tidies it up, then waits to see if he can attract a female. The female inspects the site and the male to decide if she likes them, and if she does, the pair build a nest of twigs lined with grass, and the female lays two to four eggs.

Oh, and the northern bald ibis is sometimes also called the waldrapp, just as Gessner reported.

All this information certainly sounds like the same bird Gessner described. But the northern bald ibis doesn’t live in Switzerland or other parts of Europe. It’s only known from the Middle East and northern Africa. Right?

That’s what people after Gessner thought, until 1941. That’s when a team of scientists excavating ancient sites in Switzerland found the bones of what turned out to be northern bald ibises—but the bones weren’t fossilized. They were only a few hundred years old. More remains, both fossil and subfossil, have since been found in France, Germany, Austria, and Spain, and the bird probably lived in even more areas.

It turns out that the northern bald ibis was once common in many parts of Europe, especially around the Alps. It was considered a sacred bird in ancient Egypt, and was supposed to be one of the birds released by Noah during the great flood to help him find land, so was venerated by people of different faiths in the Middle East. But in Europe, it was just considered good to eat. The Archibishop Leonard of Salzburg called for its protection in the Swiss Alps as long ago as 1504, but by the early 17th century, only a matter of decades after Gessner’s book was published, the bird was extinct in Europe. It didn’t take long for Europeans to forget it even existed.

Unfortunately, the northern bald ibis is still endangered due to hunting, habitat loss, and poisoning from pesticides. It’s also sometimes electrocuted when it lands on electricity pylons that aren’t insulated for birds, although efforts are underway to make pylons bird-safe in many areas. A successful captive breeding program has been in place since the late 1970s, though, and that’s a good thing, since the last migratory population went extinct in 1989 and the remaining non-migratory colonies declined to only a few hundred individuals.

The breeding program has gone so well that birds started being reintroduced in some areas of their former range in about 2003, including Spain, Germany, Austria, and Italy. Tagging of the remaining wild birds has also revealed that a small population still migrates from the Middle East to Africa to winter in central Ethiopia. In some areas, conservationists have added nesting platforms to the existing cliffs so that more birds can nest safely. Hopefully their numbers will continue to climb.

I’ll finish with a final piece of trivia about the northern bald ibis that I think you’ll like. It’s a member of the pelican family. Have a nice day.

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. If you like the podcast and want to help us out, leave a rating and review on Apple Podcasts or wherever you listen to podcasts. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us that way.

Thanks for listening!

Episode 172: Temnospondyls

This week let’s go back back back in time to more than 300 million years ago, when amphibian-like animals lived in enormous swamps. Don’t be fooled by the word amphibian: many Temnospondyls were really big!

Further reading:

Palaeos Temnospondyli

Dvinosaurus, three feet long and full of teeth:

And Sclerocephalus, five feet long and full of teeth. This one has a couple of larvae nearby:

Fayella (art by Nix)

Nigerpeton’s astonishing NOSE TEETH:

Mastodonsaurus had nose teeth too and it was way bigger than Nigerpeton, but somehow it just looks goofy instead of cool:

Koolasuchus just looked weird:

The largest Temnospondyl known, Prionosuchus:

Show transcript:

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

This week we’re going back into the past, way before the dinosaurs, to look at an order of animals that resembled modern amphibians but weren’t precisely amphibians, or reptiles, or fish. Let’s look at the Temnospondyls.

During the early Carboniferous period, which lasted from about 360 to 300 million years ago, the ocean levels were high, the climate across much of the world was humid and tropical, and the continents were in the process of smushing together to form a huge landmass called Pangea. Much of the land was flooded with warm, shallow water that created enormous swampy areas full of plants and newly evolved trees. These swampy areas, full of decomposing leaves, eventually became coal and peat beds. As the Carboniferous period continued, the climate turned milder and the sea levels dropped, but while the huge swamps remained, many life forms evolved to take advantage of the various habitats and ecological niches they provided.

The armored fish of the Devonian went extinct, replaced by more modern-looking fish, including sharks and the first freshwater fish. The first conifer trees appeared, land snails, dragonflies and other insects, and the first animals that could survive on land for part of the time. This included the Temnospondyls, a numerous and successful order of animals whose fossils have been found worldwide and appear in the fossil record for more than 200 million years. But most people have never heard of them.

Temnospondyls are grouped in the class Amphibia alongside Lissamphibia, which is the order all living amphibians and their ancestors belong to. But researchers aren’t sure if Temnospondyls gave rise to lissamphibians or if they all died out.

The first Temnospondyl fossils were discovered in the early 19th century and early paleontologists immediately started debating what exactly these strange animals were. It was originally classified as a reptile, but as more fossils came to light, it became clear that these weren’t reptiles. Finally it was classified as a subclass of amphibian called Labyrinthodontia, where it remains today, at least for now.

Temnospondyls do share many traits with modern amphibians. We know that at least some species had a larval form that was completely aquatic, with fossil evidence of gill arches. Some retained external gills into adulthood the way some salamanders do. But they still had a lot in common with their fish ancestors.

Most Temnospondyls had large heads that were broad and flattened in shape, often with a skull that was roughly triangular. The earliest species had relatively small, weak legs and probably spent most of their time in the water, but it wasn’t long before species with stronger legs developed that probably lived mostly on land.

When you think about amphibian relatives, you probably think these animals were small, maybe the size of a bullfrog. But while some Temnospondyls were small, many grew much larger. Some had smooth skin but many had scales, including some species with scales that grew into armor-like plates. Let’s look at some individual species of Temnospondyl and get an idea of how varied they were.

Let’s start with a group of temnospondyls with one of the most confusing names ever, Dvinosauria. That may not sound too confusing, but it’s spelled just like dinosauria but with a V after the D. It lived in the late Permian around 260 million years ago, and its fossils have been found in parts of Russia. It was named not to mess with people who keep seeing dvinosaur and thinking dinosaur, but after the Northern Dvina River.

Dvinosaurs were either semi-aquatic or fully aquatic, depending on the species. The genus Dvinosaurus was pretty typical for aquatic Temnospondyls. It had external gills and was fully aquatic, with small legs but a powerful tail for swimming. It grew over three feet long, or around a meter, and probably looked like a big salamander with a big triangular head. It probably ate fish and other small animals. Like many Temnospondyls, it had extra teeth growing from the roof of its mouth to help it hold onto fish. Some paleontologists think it lurked at the bottom of rivers and streams until it saw a fish or other animal approach, at which point it shot upward and grabbed it.

A typical land Temnospondyl was Sclerocephalus, which lived around 300 million years ago in what is now Germany. We have a lot of Sclerocephalus fossils, which means it was probably a successful animal. It was also big, around five feet long, or 1.5 meters.

Because we have so many Sclerocephalus fossils, we know a lot more about it than we do other Temnospondyls. Its larval form was aquatic and had a long tail to help it swim. As a juvenile it probably had external gills but as it matured, it spent more and more time on land, using its lungs to breathe. Its tail was shorter as an adult because it didn’t need to swim as often. But it did spend time in the water and retained the lateral line system still found in fish and some amphibians, a sensory organ that detects water movements. It also had a pineal eye that a few animals retain today, notably the reptile Tuatara that we talked about way back in episode three. This third eye was at the top of the skull and was probably only sensitive to light rather than being useful for seeing. As in modern animals that still have a pineal eye, it probably helped regulate behaviors according to the length of days.

We even know exactly what Sclerocephalus ate, because we have fossilized stomach contents in a few cases. It ate fish and amphibians and sometimes smaller Sclerocephaluses, and was probably an opportunistic predator. Like other Temnospondyls it had teeth on its palate, three pairs in its case that grew from the roof of its mouth.

A less typical temnospondyl was the genus Fayella, which lived in what is now Oklahoma in the United States and lived around 270 million years ago, in the early Permian. It grew to about four feet long, or 1.15 meters, and had unusually long legs for a Temnospondyl. It also had a smaller head in proportion to its body compared to most Temnospondyls, and was more lightly built. As a result, it looked more like a reptile or an early synapsid, which as you may remember from episode 119 were proto-mammals that looked like weird reptiles. Researchers think Fayella could run much faster than other Temnospondyls could, which didn’t so much help it catch prey as evade hunting synapsids.

Nigerpeton looked more like your average Temnospondyl, mostly. It lived in what is now the African country of Niger, around 250 million years ago. It was only discovered in the early 2000s and we still don’t have very many fossils so we don’t know exactly how big it was. But its skull was two feet long, or 60 cm, so it was definitely a big animal. It probably looked a lot like a crocodile in many ways, including a long, heavy snout with lots of teeth. Lots of teeth. LOTS of teeth. As with other Temnospondyls, it ate fish and other small, wriggly animals, and to help it catch those fish it had ordinary teeth and extra teeth that grew from the top of the mouth and the lower jaw. Basically it just had a mouthful of teeth. This is true for many Temnospondyls, but Nigerpeton took that one step too far. Two of its extra teeth are referred to as tusks, because they grew upward from the lower jaw, pierced through the roof of the mouth, and emerged from the top of the nose about where you’d expect nostrils to be in a modern animal. Instead of nostrils, NOSE TEETH. Actually, the nostrils were behind the nose teeth. We don’t know enough about Nigerpeton to know what it used these tusks for, but it sure looked cool.

Nigerpeton wasn’t the only Temnospondyl with tusks that emerged from the top of the nose when its mouth was closed. Others had it too, including one of the first Temnospondyls discovered, Mastodonsaurus. Mastodonsaurus was a successful genus of Temnospondyls that lived from about 247 million years ago to 201 million years ago in what is now Europe. Despite its name, Mastodonsaurus was neither a mastodon nor a dinosaur. It was big, though—one species grew up to 20 feet long, or 6 meters. Like other Temnospondyls it had a big head and a somewhat short tail. It also had legs that were small and weak, which suggests it was mostly if not completely aquatic, and it ate fish and other small animals.

The most recently living Temnospondyl, which went extinct around 120 million years ago, lived in what is now Australia. Koolasuchus lived in fast-moving streams and filled the same ecological niche as crocodiles, which eventually replaced it after it went extinct. But it didn’t look anything like a crocodile. It had the typical big head of a Temnospondyl, in this case broad and rounded with a blunt nose, but with what are called tabular horns that projected from the rear of the skull, which gave its head a triangular appearance. Plus, it probably grew up to 16 feet long, or 5 meters. But its body was relatively slender compared to the chonky head, which made it look kind of like a really really big tadpole.

We’ll finish with the largest species of Temnospondyl known, Prionosuchus. It lived between 299 and 272 million years ago in what is now Brazil, and while it didn’t look much like a modern crocodile, it filled the same ecological niche. It had relatively small legs and a big head like most Temnospondyls, but its snout was slender and elongated like a ghavial’s. It was an aquatic animal and was probably an ambush predator that mostly ate fish.

While we don’t know exactly how big Prionosuchus could grow since we don’t have any complete specimens, the largest skull found measured 5.2 feet long, or 1.6 meters. That’s just the skull. Researchers estimate the animal was 30 feet long, or 9 meters, when it was alive.

But although Prionosuchus was amphibious like other temnospondyls, it retained a lot of features from its fish ancestors. Basically, it looked something like the biggest salamander you could imagine, but with jaws and teeth like a ghavial’s, but inside it was more fish than amphibian. It’s no wonder paleontologists have been trying to figure Temnospondyls out for almost two centuries.

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. If you like the podcast and want to help us out, leave a rating and review on Apple Podcasts or wherever you listen to podcasts. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us that way.

Thanks for listening!

Episode 171: The Animals of St. Kilda

Thanks to Emma for the suggestion! Let’s learn about some animals that live on the St. Kilda islands off the coast of Scotland!

St. Kilda:

Soay rams (kept on farms, not the feral sheep):

A small flock of Soay sheep (these are from a farm too):

A Boreray ram (on a farm):

A Boreray ewe with her babies (also on a farm, or at least I think so):

The St. Kilda wren (not a sheep):

The St. Kilda field mouse (also not a sheep) is the size of a hamster:

Show transcript:

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

This week’s episode is a suggestion from Emma, who long ago told me about the interesting history and unique animals of the island of St. Kilda in Scotland. I’ve been meaning to cover it ever since, so finally I’m getting around to it after only two years or so.

Emma says, “It’s an amazing little island and sort of a reverse of the usual ‘humans cause extinction’ story. The humans on the island went ‘extinct’, being evacuated from the island partly because increased mainland human contact was bringing illnesses they couldn’t fight without hospitals. Two lots of rad ancient sheep and some unique wrens and mice are happily living there to this day.”

St. Kilda is not one but a group of islands off the coast of Scotland, but the largest island and the only one where people once lived is called Hirta. In 1930, everyone who still lived there moved to the mainland, but by that time hardly anyone remained on St. Kilda anyway. The island probably never had more than a few hundred people in residence at any given time. In 1957 St Kilda was designated as a nature reserve and in 1986 as a World Heritage Site.

Since then, as Emma says, the animals of the islands have mostly been left alone. This includes two breeds of sheep that were left behind on two of the smaller islands when the last residents moved away.

One of these sheep breeds is the Soay, which originally lived on a tiny island called Soay, which actually means “sheep island.” The island of Soay is only about 250 acres in size, or 100 hectares, but that’s not the only place they used to be found. The breed has lived in northern Europe for probably 4,000 years, and was a popular sheep in Britain for centuries. When all the people moved away, 107 sheep living on Soay were moved to Hirta. The sheep on Hirta are feral and receive no care from humans, but they also have basically no predators on the island. They have been studied since 1955 by a small team of scientists and conservationists.

The Soay is a primitive breed of sheep that closely resembles its wild ancestor, the Asiatic mouflon. It’s brown, usually with lighter markings on the face and rump, and the rams often grow a short mane of hair in addition to wool. Rams have dark brown horns and ewes often grow smaller horns too. It also has a short tail. In late spring, Soay sheep shed their fleece naturally instead of needing to be shorn. This is the case with many primitive sheep breeds. Its wool is considered high quality and sought after by handcrafters.

Also like many primitive breeds, the Soay doesn’t have much of a flocking instinct. Soay sheep have been exported from the islands and are kept on farms in many areas for their wool, but if a sheep dog tries to herd a flock of Soay, the poor dog is going to be so frustrated. Soay scatter instead of flocking together. It can also be an aggressive sheep, especially the rams, but it’s also a small breed, with even a big ram rarely heavier than 70 lbs, or 32 kg. And these days, the feral Soay sheep are actually getting smaller overall and have been for the last twenty years. The research team that studies the sheep thinks it’s because climate change has led to shorter, warmer winters, which allows more of the sheep to survive, including smaller sheep that would ordinarily have trouble in cold weather. The smaller sheep breed and their offspring are more likely to be small too, and after twenty years of this the breed overall is smaller than it used to be.

While the Soay used to be a popular breed throughout much of Europe, it’s an at-risk rare breed these days. There are fewer than 1500 breeding ewes registered on farms, in addition to the feral flock on Hirta.

The other breed of St. Kilda sheep is called the Boreray, and it’s also a feral sheep on one of the St. Kilda islands. In this case it lives on the island of Boreray. It’s even rarer than the Soay sheep, the rarest sheep breed in the UK. In 1999 there were only 84 individuals known, but a conservation effort by the Rare Breeds Survival Trust has increased the number to nearly 900 breeding ewes as of 2018.

The Boreray is a little smaller than the Soay and shares characteristics with that breed, including a short tail and its fleece shedding naturally in late spring. It’s usually gray or white, although sometimes brown, often with a speckled black face. Its wool is much coarser than the Soay’s and was traditionally used to make tweed fabric or carpets.

But sheep are domesticated animals, feral or not. What about some of the other animals of St. Kilda?

The St. Kilda wren is a subspecies of Eurasian wren that’s found nowhere else in the world. Like other wrens it’s a tiny songbird, brown and gray with a short tail. It was only recognized as a separate subspecies in 1884, and as happened a lot in those days, museum collectors killed so many of them to stuff and mount that the bird nearly went extinct. Fortunately, early conservationists realized the danger in time, and a special Act of Parliament in 1904 protected the bird. After all the people were evacuated from Hirta, a small team of scientists studied the wren. In 1931 68 nesting pairs were counted, and in 2002 230 breeding pairs were counted. That’s still a low population, but since the wren has almost no predators on St. Kilda, that’s a decent number for such a small habitat.

The St. Kilda wren eats insects, spiders, and other small invertebrates. The male builds the nest out of dead grass and other plants, moss, and seabird feathers.

This is what the St. Kilda wren sounds like:

[St Kilda wren singing]

Another animal found nowhere else in the world is the St. Kilda field mouse, a subspecies of wood mouse. There used to be another mouse subspecies found only on St. Kilda, the St. Kilda house mouse. Both mice were described in 1899, and both are larger than mainland mice. But because the house mouse is dependent on humans, once everyone evacuated the islands the St. Kilda house mouse went extinct within two years.

But the field mouse was fine, and is common throughout the island of Hirta and at least one other island. It actually moved into the abandoned buildings after the house mice went extinct, since houses are full of little nooks and crannies that mice can use as homes. Researchers think the mouse may have been on the islands for something like a thousand years, arriving with Viking settlers.

The St. Kilda field mouse is twice as large and heavy as mainland mice, probably because it basically has no predators. It’s an omnivore like most other mice, and eats seeds, moss, insects and other small animals, and even scavenges meat from dead sheep and birds.

Many sea birds nest on St. Kilda, including Atlantic puffins and northern gannets. The grey seal started breeding on Hirta after everyone left. But except for the sheep, the mice, and the gray seals coming ashore during breeding season, there are no other mammals living on St. Kilda. There are also no trees, no bees, and a limited number of plants and animals, all due to how remote the islands are. They’re 41 miles, or 66 km, away from the Outer Hebrides, a series of much larger islands off the Scottish coast.

Humans have probably lived on Hirta for two thousand years, maybe longer, and have visited the St. Kilda islands as long as 5,000 years ago. But now that the people are gone, the mice and sheep and birds are free to live their quiet lives. As long as they don’t mind a few curious scientists keeping an eye on them.

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 at patreon.com/strangeanimalspodcast if you’d like to support us and get twice-monthly bonus episodes for as little as one dollar a month.

Thanks for listening!

Episode 170: Spinosaurus

This week let’s find out what has paleontologists so excited about this dinosaur!

Further reading:

The Nature article that kicked this all off (you can only read the abstract for free but it’s full of good information)

Paleontologist Who Uncovered Prehistoric River Monster’s Tail Explains Why It’s Such a Game Changer (Newsweek)

Further watching:

A good video about the new findings

Spinosaurus’s updated look:

This trackway from a swimming animal may have been made by a Spinosaurus (photo by Loic Costeur):

A male Danube crested newt, with a tail that somewhat resembles that of Spinosaurus:

Show transcript:

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

If you follow any paleontologists on social media, you’ve probably heard them talking about the new spinosaurus article just published in Nature. It sounds like the sort of discovery that makes other paleontologists take a closer look at fossils of dinosaurs related to spinosaurus, so this week let’s find out what the discovery is and what it means!

I could swear we’ve talked about Spinosaurus before, but a quick search revealed that we actually learned about its relative, Baryonyx, in episode 151. Baryonyx grew at least 33 feet long, or 10 meters, and lived around 125 million years ago. It had a skull similar to Spinosaurus’s but otherwise didn’t resemble it that much, and as far as we know it waded in shallow water to catch fish and other aquatic animals.

Spinosaurus was a therapod dinosaur that lived in the Cretaceous, roughly 112 to 93 million years ago. It lived in what is now North Africa and the species we’re talking about today is Spinosaurus aegyptiacus, which as you can probably guess was first discovered in Egypt.

Spinosaurus was as big as Tyrannosaurus rex, possibly larger depending on what measurements you’re looking at. It could probably grow some 52 feet long, or 16 meters, possibly as much as 59 feet long, or 18 meters. But it didn’t look very much like a T. rex. For one thing, its front legs were large and strong. Instead of T. rex’s massive skull and jaws, Spinosaurus had a more slender, narrow skull that was shaped something like a crocodile’s. It also had long neural spines on its back that may have formed a type of sail similar to Dimetrodon’s, although of course Spinosaurus and Dimetrodon weren’t related at all. Dimetrodon wasn’t a dinosaur or even technically a reptile, as we learned in episode 119.

Spinosaurus’s neural spines could grow almost five and a half feet long, or 1.65 meters, and if they did form a sail, it was roughly squared off instead of shaped like a half-circle. Some researchers think it wasn’t a sail at all but a fatty hump on its back something like a buffalo’s shoulder hump or a camel’s humps. The neural spines would help give the hump structure. Other researchers think it was a sail used for display, while one team of paleontologists suggested as early as 2014 that it was a sail that acted as a dorsal fin in the water, since it’s shaped like a sailfish’s dorsal fin.

Spinosaurus probably ate both meat and fish, so it makes sense that it lived in swampy areas like mangrove forests and tidal flats where it could hunt both terrestrial and water animals. Its hind legs were short, its feet were flat with long toes, and its toes may have been webbed. Its hind feet actually share features found in modern shorebirds, which suggests it spent a lot of time walking on soft ground like sand, marsh, and shallow water.

Despite its body length and short legs, Spinosaurus walked on its hind legs. Its tail was very long to balance the front of its body. And it’s the tail that is the focus of the Nature article everyone’s talking about right now.

See, despite Spinosaurus’s fish-eating, almost no one thought it was an aquatic dinosaur. No one thought any dinosaur swam around routinely to catch fish. The big predators that lived in oceans and fresh water at the same time as the dinosaurs were not dinosaurs, but were reptiles like the crocodile and Mosasaurus.

A few paleontologists, like the team that suggested Spinosaurus’s neural spines formed a sort of dorsal fin, had started suggesting Spinosaurus and its close relations were semi-aquatic. But almost no one agreed. Most scientists pointed out that Spinosaurus looked like an ordinary wading animal, not a swimming animal.

Then, in an article published in Nature on April 29, 2020, a new study revealed that Spinosaurus’s tail isn’t the ordinary long, skinny dinosaur tail. Instead, new physical models of its tail show “unambiguous evidence of [the tail acting as] an aquatic propulsive structure”. In other words, Spinosaurus could not only swim, it could probably swim quite well.

Its tail had tall neural spines like the ones on its back, some of them two feet long, or 61 cm, which gave it more surface area to push against the water. It was flexible and strong too.

So how come no one had noticed this before? Well, no one had the right fossils. Most of the tail bones studied were only found in 2018 and 2019 in Morocco by a team of Italian paleontologists. And guess what! The team of paleontologists were the same ones who suggested a few years ago that the neural spines on Spinosaurus’s back acted as a dorsal fin, led by a man named Nizar Ibrahim. While we still don’t know for sure, it’s looking more and more like they were correct. A dorsal fin provides stability in the water, and of course it could also act as a display feature to attract mates.

We don’t have very many Spinosaurus fossils. The only good specimen ever found was destroyed by a bomb in World War II, and it didn’t have a tail anyway. Until the 2018 expedition started turning up Spinosaurus vertebrae, no one knew what the tail looked like at all. The expedition found most of its tail and a lot of the rest of its bones, including part of the skull. While the fossils were found in the Sahara, back when Spinosaurus was alive the area was swampy and full of rivers, home to lots of large animals, including coelacanths and crocodiles. But Spinosaurus was probably the largest.

There is an animal that has a similar body plan to Spinosaurus’s, an amphibian called the Danube crested newt. It lives in parts of central Europe. It grows to about 7 inches long, or 18 cm, although males are smaller. It’s dark brown with black and white spots and an orange belly with larger black spots. During breeding season, the male develops a crest on its back and tail that does look a little bit like Spinosaurus’s sails. During the fall and winter it lives in the forest, but the rest of the year it lives in water. It eats small animals like insects and tadpoles.

The paleontologists studying Spinosaurus’s tail made a model of the Danube crested newt’s tail and some other animal tails and tested them to see which tail worked best to provide thrust underwater. The newt’s tail won.

That doesn’t mean Spinosaurus was necessarily a fast swimmer. The tail alone would allow it to move forward at around five miles an hour, or 1.6 km per hour. You can walk faster than that with a little effort. But if Spinosaurus also had webbed feet, it could have used them for extra propulsion in the water. It may have cruised through the water at a leisurely pace and ambushed unwary fish and other animals. In shallow water it could have used its hind feet to push off the bottom while it remained buoyant, and in fact we even have fossilized underwater tracks that may be made by Spinosaurus.

Other Spinosaurids were probably at least semi-aquatic too, although they don’t seem to be as well adapted to the water as Spinosaurus was. But now that they know what to look for, it could be that paleontologists will discover more evidence of aquatic dinosaurs soon.

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