- Episode 509: Two Big Weird Heavy Animals

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

It’s taking forever to shake this cold. I feel fine now, but I still sound pretty bad. I apologize for my voice this time, but hopefully it’s not too bad. Rather than postpone this episode until my voice recovers, let’s just have a short but info-packed episode about some weird big animals from the past.

I think Llewelly alerted me to Neoparadoxia cecilialina, which appears in the fossil record between about 32 to 10 million years ago. It lived along the coast of the northern Pacific Ocean. It grew to around 8 feet long, or just under 2.5 meters, although the only specimen found so far wasn’t fully grown so it may have been a bit larger as an adult. It was a heavy animal with long legs, big feet, a big wide snout with eyes near the top of its head, and a tiny tail. In fact, it probably looked superficially like a weird hippopotamus. Like the hippo, it ate water plants. It was probably fully aquatic, meaning it lived its entire life in water.

Neoparadoxia was a member of the order Desmostylia, which were all marine herbivores that probably mostly ate kelp. They all looked sort of like weird hippos but acted more like dugongs. Some researchers think Desmostylians went extinct when dugongs evolved and outcompeted them.

Despite its strong-looking leg bones, many species of Desmostylia had spongy bones. This made the bones less dense but also weakened them. Weaker bones are not a problem for an ocean animal whose weight is supported by the water, but it does mean that it probably couldn’t support its weight on land. Whales and other cetaceans have a similar type of spongy bone.

Desmostylus was a Desmostylian genus. It probably spent most of its time near the surface of shallow water. It may have preferred to live around the mouths of rivers and spent part of its time in fresh water, part in brackish water where the ocean and river mixed. It grew around 6 feet long, or 1.8 meters, and it had toenails that were the remnants of hooves from when its ancestors lived on the land. It had two pairs of tusks that jutted forward from its long jaws, which it probably used to help dig up plants.

Some species of Desmostylia had teeth that are similar to elephant teeth, which may have helped it deal with sand and grit when eating a diet of sea grass. Species that didn’t have spongy bones may have actually walked across the sea floor to eat plants, only surfacing to take breaths.

So are Desmostylians more closely related to elephants or hippos or whales or dugongs? How about none of the above. Scientists are still trying to figure out how the Desmostylians were related to each other and to other animals, but so far they seem to be not very closely related to anything alive today. One suggestion is that they’re basal odd-toed ungulates that completely died out around 10 million years ago, leaving no living descendants.

Another group of big heavy weird animals that went extinct around 28 million years ago was an order called Embrithopoda. Instead of looking sort of like hippos, Embrithopods looked more like rhinoceroses. They were land animals that probably evolved in Africa, although they also lived in parts of Eurasia, and they were probably about as closely related to Desmostylians as Desmostylians were to elephants and dugongs—and, in fact, Embrithopods were probably also distantly related to elephants and dugongs. They probably weren’t actually related to rhinos.

This is weird at first glance, because Embrithopods look a lot like rhinos. Some species even had nose horns. For instance, Arsinoitherium lived in the rainforests of northern Africa around 30 million years ago, and stood around 6 feet tall at the shoulder, or 1.8 meters, and had a pair of huge horns on the nose with another small pair over the eyes. But the nose horns were much different from the rhino’s horn. For one thing, both were side by side. For another, they weren’t made out of keratin fibers like the rhino’s horn. Instead, the horn cores were made of bone and were probably covered with keratinized skin something like giraffe ossicones. Either way, they were probably pretty darn impressive, especially if they were pointed at you.

Embrithopods ate plants, especially tough plants. Some species may have been semiaquatic, living in swampy areas and in lakes. And that is pretty much all we know about them. I kind of want one as a pet after looking at pictures of its skeleton, but let’s just chalk that up to the cough medicine I’ve been taking.

Thanks for your support, and thanks for listening!