Tag Archives: Gondwanatheria

Episode 330: Vintana and Tiarajudens

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Thanks to Lorenzo for suggesting Tiarajudens! We’ll learn about it this week along with another extinct animal, Vintana.

Further reading:

Funky facial flanges [the skull picture below comes from this site]

First Postcranial Fossils of Rare Gondwanatherian Mammal Unearthed in Madagascar

The Earliest Saberteeth Were for Fighting, Not Biting [the skeleton picture below comes from this site]

Vintana’s skull had weird jugal flanges:

Tiarajudens had saber teeth as well as palatal teeth:

Show transcript:

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

Just last month we had an episode about the tenrec and an extinct animal called Adalatherium. At the end of that episode, I said something I say a lot, that we don’t know very much about it or the other ancient mammals that lived at the time, and that I hoped we would find some new fossils soon. Well, guess what! A paper about a newly discovered Gondwanathere fossil was published just a few days ago as this episode goes live. Rather than save it for the updates episode later this summer, let’s learn about an animal named Vintana sertichi, along with a suggestion from Lorenzo for another extinct animal.

As you may remember from episode 324, Adalatherium is a member of a group of animals called Gondwanatheria, which arose in the southern hemisphere around the time that the supercontinent Gondwana was breaking apart. We only have a few fossils of these animals so paleontologists still don’t know how they’re related, although we do know they’re not related to the mammals living today. Every new specimen found of these rare mammals helps scientists fill the gaps in our knowledge. That’s what happened with Vintana.

Vintana lived at the end of the Cretaceous, until the asteroid strike about 66 million years ago that killed off the non-avian dinosaurs and a whole lot of other animals, probably including Vintana. The first fossilized specimen was a skull found in Madagascar and described in 2014. It was really well preserved, which allowed scientists to learn a lot about the animal.

Vintana was an active animal that ate plants. It had large eyes and a good sense of smell and hearing, so its ears might have been fairly large too. Its face probably looked a lot like a big rodent’s face, but the skull itself had a weird feature. The cheekbones extended downward on each side next to the jaw, and these extensions are called jugal flanges. They would have allowed for the attachment of really big jaw muscles. That suggests that Vintana could probably give you a nasty bite, not that you need to worry about that unless you find a time machine. It might also mean that Vintana ate tough plants that required a lot of chewing.

Vintana probably looked a lot like a groundhog, or marmot, which we talked about recently in episode 327. It wasn’t related to the groundhog, though, and was bigger too. Scientists estimate it weighed about 20 lbs, or 9 kg.

The fossil specimen of Adalatherium that we talked about in episode 324 was discovered in Madagascar in 2020. When a tail vertebra from another mammal was found in the same area, researchers scanned and compared it to Adalatherium’s vertebrae. They were similar but not an exact match, plus the new bone was almost twice as large as the same bone in Adalatherium’s spine. It matched the size of Vintana and was assigned to that species. Vintana was probably related to Adalatherium but was bigger and had a shorter, wider tail. And as of right now, that’s just about all we know about it.

Next, let’s learn about another extinct animal, this one suggested by Lorenzo. Lorenzo gave me a bunch of great suggestions and I picked this one to pair with Vintana, because otherwise this episode would have been really short. Vintana lived at the end of the dinosaurs, but Tiarajudens lived long before the dinosaurs evolved, around 260 million years ago.

Tiarajudens was a therapsid, a group that eventually gave rise to mammals although it’s not a direct ancestor of mammals. Technically it’s an anomodont. We don’t have a complete skeleton so we don’t know for sure how big it was, but we do have a skull and some leg bones so we know it was about the same size or a little bigger than a big dog. There are only two species known, one from what is now South America and one from what is now Africa, but 260 million years ago those two landmasses were connected and were part of the supercontinent Gondwana.

Tiarajudens had weird teeth even compared to other anomodonts. It had a pair of saber teeth that resembled the tusks found in later anomodonts, but they weren’t really tusks. They were big fangs that grew from the upper jaw and jutted down out of the mouth well past the bottom of the jaw. Later anomodonts probably used their tusks to dig up plants, but there aren’t wear marks on Tiarajudens’s saber teeth that would indicate it used them for digging. Many paleontologists think it used them for defense and to fight other Tiarajudenses over mates or territory. We don’t know if the saber teeth were present in all individuals, since we’ve only found a few specimens.

Tiarajudens also had palatal teeth. These days palatal teeth are mostly found in amphibians, especially frogs. Palatal teeth grow down from the roof of the mouth and Tiarajudens’s were flat like molars. We haven’t found a lower jaw yet so we don’t know what the bottom teeth looked like, but from the wear marks on the upper teeth, it was clear that Tiarajudens was actually chewing its food. That was really unusual among all animals at the time, and in fact Tiarajudens is one of the first animals to really chew its food instead of giving it a chomp or two and swallowing it mostly whole. It ate plants, probably tough ones that required a lot of chewing.

So what did Tiarajudens look like beyond its teeth? It probably resembled a bulky four-legged dinosaur with a short tail, but it may have had whiskers. That’s as much as we know right now, because Tiarajudens was not only an early therapsid, it was different in many ways from most other therapsids known. For instance, it had what are called gastralia, or belly ribs, which were once common in tetrapods. Some dinosaurs had gastralia, including T. rex, but most therapsids didn’t. These days crocodiles and their relations still have gastralia, and so does the tuatara, but most animals don’t.

Both Tiarajudens and Vintana were unusual animals that we just don’t know much about. Let’s hope that changes soon and scientists find more fossils of both. I’ll keep you updated.

You can find Strange Animals Podcast 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 us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 324: The Tenrec and Adalatherium

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We have merch available again!

Thanks to Eva and Leo for suggesting the tenrec!

Further reading:

Marooned on Mesozoic Madagascar

Introduction to Adalatherium hui

The lowland streaked tenrec:

The hedgehog tenrec rolls up just like an actual hedgehog [photo by Rod Waddington, CC BY-SA 2.0, via Wikimedia Commons]:

Actual hedgehog, not a tenrec:

Lesser hedgehog tenrec REALLY looks like an actual hedgehog [By Wilfried Berns www.Tierdoku.com – Transferred from de.wikipedia to Commons.Orig. source: eigene Fotografie, CC BY-SA 2.0 de, https://commons.wikimedia.org/w/index.php?curid=2242515]:

Adalatherium:

Show transcript:

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

This week we’re going to learn about a weird little animal suggested by both Eva and Leo, the tenrec of Madagascar. While we’re at it, we’re going to learn about another little animal found on Madagascar a long time ago that’s one of the weirdest mammals ever discovered.

Before we get started, though, someone sent me a book! If your name is Jennifer or someone named Jennifer mailed this book to me for you, thank you! The book is called The Last Flight of the Scarlet Macaw: One Woman’s Fight to Save the World’s Most Beautiful Bird by Bruce Bercott. Thank you so much! I did not know when I started this podcast over six years ago that one of the benefits of doing an animal podcast is sometimes people send you books about animals, which is the best thing in the world. There’s no note so I thought I’d give you a shout-out on the podcast.

As we learned in episode 318, about 88 million years ago, the island of Madagascar broke off from every other landmass in the world, specifically the supercontinent Gondwana. The continent we now call Africa separated from Gondwana even earlier, around 165 million years ago. Madagascar is the fourth largest island in the world and even though it’s relatively close to Africa these days, many of its animals and plants are much different from those in Africa and other parts of the world because they’ve been evolving separately for 88 million years.

But at various times in the past, some animals from Africa were able to reach Madagascar. We’re still not completely sure how this happened. Madagascar is 250 miles away from Africa, or 400 kilometers, and these days the prevailing ocean currents push floating debris away from the island. In the past, though, the currents might have been different and some animals could have arrived on floating debris washed out to sea during storms. During times when the ocean levels were overall lower, islands that are underwater now might have been above the surface and allowed animals to travel from island to island until they reached Madagascar.

Sometime between 25 and 40 million years ago, a semiaquatic mammal reached Madagascar in enough numbers that it was able to establish itself on the island. It was related to the ancestors of a semiaquatic mammal called the otter-shrew, even though it’s neither an otter nor a shrew. The otter-shrew lives in parts of Africa and is pretty weird on its own, but we’ll save it for another episode one day. The otter-shrew’s relative did so well in its new home of Madagascar that over the millions of generations since, it developed into dozens of species. We now call these animals tenrecs.

It’s hard to describe the tenrec because the various species are often very different in appearance. There are some things that are basically the same for all species, though. First, the tenrec has a low body temperature, although it varies from species to species and also varies depending on time of year. That’s because some species of tenrec go into torpor when it’s cold, or sometimes full hibernation. During torpor the animal’s body temperature drops even more than usual. The common tenrec hibernates up to nine months out of the year.

Second, the tenrec has a cloaca, which is really unusual in placental mammals. Birds, reptiles, and amphibians have a cloaca, which is a single opening used for excretion and often for giving birth or laying eggs too. Most mammals have separate openings for different uses.

Third, all tenrecs are pretty small with only a little short tail. The biggest is only a little over a foot long at most, or 39 cm, and most are much smaller.

Leo specifically likes the streaked tenrec, so let’s learn about it to give us a better idea of what tenrecs are like in general. There are two species of streaked tenrec and while they live in different parts of Madagascar, they mostly live in tropical rainforests. They’re considered a type of spiny tenrec because they have quills all over like a tiny porcupine or a brightly colored hedgehog. The highland streaked tenrec is black and white, while the lowland streaked tenrec is black and yellow.

The streaked tenrec’s bright coloration gives a warning to potential predators that it is pointy. If a predator doesn’t figure it out, the tenrec will raise its quills and shake them to make a little rattling sound. If that doesn’t stop the predator and it tries to bite the tenrec, the quills can detach and will lodge in the predator’s mouth. That generally gets the point across. (haha, point)

The lowland streaked tenrec also communicates by rubbing its quills together to make ultrasonic sounds. This method of sound production is called stridulation and the streaked tenrec is the only mammal known to make sound this way. It has special muscles at the base of its quills that help it move the quills to make sounds. Stridulation is mostly found in insects, including crickets.

Like most tenrecs, the streaked tenrec has a long, thin snout and short legs. It spends a lot of its time digging for earthworms and other invertebrates, and it also eats fruit. It lives in family groups that sleep in shallow burrows. Also, it’s super cute. Just don’t lick it.

Another tenrec with spines is the hedgehog tenrec, which looks and acts incredibly like a hedgehog even though it’s not related. That’s yet another example of convergent evolution. The lesser hedgehog tenrec and the greater hedgehog tenrec, which by the way belong to different genera, are nocturnal animals that live in open forests, savannas, and people’s gardens in Madagascar. During the day it stays hidden in dead leaves or brush, or in a hollow of a tree trunk, and at night it comes out to find insects and other small animals to eat. If it feels threatened, it will roll up into a ball to protect its belly while turning itself into a very pointy mouthful. Its spines don’t come loose the way the streaked tenrec’s do, but they’re sharp. Sometimes a hedgehog tenrec will back up quickly toward a potential predator. If it backs into the predator’s nose, suddenly the predator discovers it’s not all that hungry and its nose hurts and it’s just going to leave.

Many species of tenrec resemble shrews. They’re smaller than a mouse, which they otherwise resemble except that they have a long nose and short tail, and they don’t have quills. Most tenrecs have 6 or 8 babies at a time, but some have more. The common tenrec can have up to 32 babies at a time. It has 29 teats! That’s the most teats known in any mammal.

All this is amazing, but while I was researching the tenrec I learned about an even weirder animal that lived on Madagascar at the end of the Cretaceous. That animal wasn’t a dinosaur, though. It was a mammal.

It was discovered by a team of paleontologists in 1999, but they didn’t actually know they’d discovered it. They thought the piece of rock only contained a small crocodyliform. When preparation of the specimen started in 2002, the scientist working on it received an incredible surprise. In addition to fossil remains of both an adult and a baby crocodyliform, there was an almost complete, articulated skeleton of a weird mammal. All three animals may have been buried suddenly by debris carried by a flash flood, which is why they’re so well preserved.

Most mammals that lived alongside dinosaurs were really small, maybe the size of rats at most, but Adalatherium was about the size of a cat. It may have actually grown larger than a cat, because the only specimen we have is an individual that wasn’t fully grown. It was built sort of like a little badger, with a broad body, short legs, short tail, and short snout.

Adalatherium is a member of a group of mammals called Gondwanatheria, which arose in the southern hemisphere around the time that the supercontinent Gondwana was breaking apart. We only have a few fossils of these animals so paleontologists still don’t know how they’re related, but Adalatherium is a big deal because it’s so detailed and almost the whole skeleton is preserved. Paleontologists have known for a long time that these Gondwanatheria were probably not related to modern mammals, but until Adalatherium was discovered no one realized just how weird these animals were.

If you could go back in time to look at Adalatherium when it was alive, you might not think it was all that weird. Also, you’d be a little distracted because dinosaurs would probably be trying to eat you. Most of the weird details probably weren’t visible, but they’re very obvious to scientists studying the fossilized bones. For instance, Adalatherium had a lot of vertebrae in its backbone, more than other mammals—at least 30 total thoracic and lumbar vertebrae. Humans have 17 total and cats have 20, to give you a comparison with modern mammals.

Adalatherium also had weird legs, with its front legs not really seeming to match its rear legs. Its front legs are longer with a strong shoulder, while its rear legs are short and bowed. Paleontologists think it might have been a burrowing animal, which would explain why its rear legs are strangely shaped compared to its front legs, but it could probably run pretty fast too. It also had unusual double grooves on its anklebones.

Another weird thing about Adalatherium was its skull. The parts of the skull that made up the nasal cavity had lots of little holes in it, called foramina, for nerves and blood vessels to pass through. This isn’t unusual in itself, but Adalatherium had more foramina than any other mammal ever examined, living or extinct. One of the foramen was on top of the snout and doesn’t match up with anything seen in any other mammal. Adalatherium probably had a whole lot of very sensitive whiskers, but for all we know, all the foramina were for some other sensory structure, one that was unlike any found in modern mammals.

Adalatherium lived at the end of the Cretaceous, and it’s possible it went extinct along with the non-avian dinosaurs. Gondwanatheria in general all went extinct by around 43 million years ago and as far as we know, no living descendants are still around. But we know very little about these interesting mammals. Hopefully more fossils of Gondwanatheria in general, and Adalatherium in particular, will turn up soon so we can learn more.

You can find Strange Animals Podcast 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 us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!