Meet The Huge ‘Hypercarnivore’ That Looked Like A Cat And Weasel

sarkastodon silhouette
© Sammy33/

Written by Maxwell Martinson

Updated: October 10, 2022

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Sometime during the early to late Eocene, there was a massive predator unlike anything on earth today. If you were roaming around Eastern Asia 40 million years ago, you might have crossed paths with the Sarkastodon.

This monster weighed roughly 1,800 pounds and trundled slowly along the plains in search of prey sizeable enough to satisfy its huge frame. You’d imagine that this beast would look something like a bear, a big cat, or even a large wolf-like animal. We think of these things as land predators because, well, those are the primary land predators that we know today.

Individuals in the Sarkastodon genus were a little different, however. They might have looked a lot like cats, bears, weasels, and rodents combined. There would have been elements of each staring back at you if you were unfortunate enough to cross paths with this king of the Eocene

Let’s do a deep dive into the genus Sarkastodon and see what we can learn about this slow-moving hypercarnivore. 

The Extinct Order: Creodonta 

50 to 37 million years ago, there was another branch of the tree of life that looked a little different than any of the orders or families that we’re used to. The base of this forgotten branch is the order Creodonta, which then split into two smaller branches called Oxyaenidae and Hyaenodontidae. 

Creodonts came from the class Mammalia, but there’s some speculation about where they diverged from the orders of life that still exist today. One theory is that there was a close common ancestor between Creodonts and Carnivorans (felines, canines, bears, and many other carnivores). This theory derives from the fact that Creodonts developed canine teeth used for crushing or sheering their prey, just like members of Carnivora. 

It makes sense that those teeth would have pre-dated the evolutionary split, lending themselves to the Creodonts and Carnivorans alike. That said, these animals existed tens of millions of years ago, and there’s not always a great deal of fossil evidence to work with. 

As a result, paleontologists and researchers are not sure whether the canines of Creodonts evolved separately from Carnivorans. That means they don’t know precisely whether Sarkastodon had a close relative with, say, the ancient Short-Faced Bear or the Saber-Toothed Tiger

Saber-toothed tiger on isolated background

Researchers are not sure whether or not Sarkastodon had a close relative with the

Saber-Toothed Tiger


©Valentyna Chukhlyebova/

Hyaenodonta & Oxyaenodonta

It’s well accepted that the Creodonts split into two primary orders; Hyaenodonta and Oxyaenodonta. Both of these groups were distinguished by their sharp teeth and predatory behavior. Hyaenodonta individuals would have been slightly more dog-like in appearance, whereas Oxyaenodonts were the more weasel-cat-bear-looking variety (we know that’s vague, but these were very unusual creatures!)

Regardless of where Creodonts stood in the order of things, it’s well-known that they were some of the most abundant and dominant predators on earth for millions of years. They’ve been discovered across the globe, from the Sarkastodon fossils of Mongolia to the Machaeroides fossils found in the United States.

All of these individuals had sharp teeth, although most would have been small, dog-sized animals. Early on, they were likely some of the first mammals to emerge after the age of dinosaurs. All early Creodonts would’ve seemed like small, peculiar rodents before they evolved to hold more significant positions as predators.

Sarkastodon, as far as researchers know, was the largest Creodont ever to emerge. It might also have been the largest mammalian carnivore the world has ever seen. Unfortunately, Creodonts no longer exist on earth. 

We’re left to wonder about the life of Sarkastodon without any of its descendants to base our ideas after. There are some things that researchers are confident about, though. Let’s take a look at what sort of life Sarkastodon might have lived. 

Who Was The Sarkastodon

Sarkastodon” literally means “meaty tooth” or “flesh-tearing tooth.” That gives you an indication of its carnivorous habits. 

The teeth are very important because they offer almost all insights that we have into the life of this animal. Only skull fragments, teeth, and mandibles (jaw bones) have been discovered. The shape of the skull along with what we know about the Mongolian environment 40 million years ago shape researchers’ understandings of the animal. 

There are four primary fossil discoveries for Sarkastodon. Three of these were found in what is now Mongolia. Two were found relatively close together in eastern Mongolia, while another was discovered a few hundred miles to the west. These specimens comprise the species S. mongoliensis.

One other fossil was discovered in present-day eastern China, just a few hundred miles from the Pacific Ocean. This individual’s bones make it the only known member of the species S. henanensis. 

Relationships between Sarkastodon and the other Oxyaenodonts can illuminate certain details about the animal. For example, it’s through the taxonomical relationship to other, related fossils that we can estimate the way Sarkastodon looked. Let’s take a minute and flesh out what this beast probably looked like and why most recreations look pretty similar. 

What Did They Look Like? 

To anyone who isn’t a paleontologist or an expert accurately detailing the traits of extinct animals, the names and descriptions thrown around don’t really mean much. For example, scientific details about Sarkastodon mandibles and proposed phenotypic traits don’t give the non-expert much to work with. 

It’s much easier to think of these animals in terms of the modern animals that they looked like. So, let’s draw some basic connections between Sarkastodon and modern animals we all know and love. 

First, and most notably, this animal was very, very big. A polar bear is roughly equivalent in length and height, although Sarkastodon was likely a few hundred pounds heavier than the largest polar bears on record. Both polar bears and Sarkastodon would stand at around the same height of 2.5 meters. 

Based on the shape of the skull and the skulls of its Oxyaenodont relatives, though, its face wouldn’t have looked much like a bear’s. Instead, it would be sort of beaver-like. For a clearer image, close your eyes and imagine your best “otter-dog” face. 

Now that you’ve got the image of a lumbering, monstrous canine-rodent, top it off with a long tail, similar to that of a tiger’s. Once you’ve got that, friends, you’re imagining humanity’s best guess as to what a Sarkastodon might have looked like. 


Experts’ best guess as to the Sarkastodon’s appearance: a very large animal, somewhat like a bear, somewhat like a


, with a beaver-like face.


Plantigrade Locomotion

As it walked, it would have had the same strut as a bear. If not in the way that its legs moved, at least in the way that its paws landed on the ground. Oxyaenodonts, as far as we know, walked with plantigrade locomotion.

That’s the same style as bears, humans, rabbits, and many others. Plantigrade locomotion means that the animal walks with its heels and toes on the ground rather than walking only on its toes or nails (like hooved animals).

The disadvantage of this is that we plantigrade animals run a little slower than our hooved counterparts. The good part, especially for bears and Sarkastodon, is that we have a firmer foundation from which to press and use our weight.

In the case of the large hypercarnivores, that means lunging forcefully into prey and making a kill with the help of fully-developed canines. That’s what allowed Sarkastodon to dig into the rhinoceroses of old, as we’ll see in the next section.

What Were Its Eating Habits?

Its size compared with the nature of its teeth suggest that it was a “hypercarnivore.” This is simply the name for an animal that gets most if not all of its sustenance from meat. An animal that weighs a whopping 1,800 pounds and eats only meat likely had some massive prey sources. 

Researchers think that Sarkastodon was feeding primarily on beasts that would have looked like rhinos and horses. Vast stretches of Eurasia have been welcoming for the development of all kinds of life through the ages. 40 million years ago, the predecessors of ungulates and carnivores flourished there. 

Over the course of the last glacial maximum, this area was called the “mammoth steppe,” and proved to be one of the only suitable environments for large herbivores like mammoths, horses, rhinoceroses, bison, and other animals that we know today. Throughout that time, the wellness of massive herbivores provided giant carnivores with the meat they needed to survive. 

Sarkastodon got so much meat, in fact, that it’s believed to have maxed out the size threshold for a terrestrial carnivore in that area. Herbivores can get much larger because there’s enough plant matter to support a monstrous frame, but carnivores can only get so big. 

There’s only so much time, energy, and prey to fuel. An effective predator like Sarkastodon likely reached the capacity for size in its ecosystem. If Sarkastodon individuals were born any larger than their parents, odds are that the environment wouldn’t have provided them with enough food to flourish.

We see this happen in modern carnivores as well, and some animals can get a lot bigger under artificial circumstances. Bears, for example, can get much larger when fed and kept in captivity. Wild bears are constrained by the ecosystem, however.  

Woolly Mammoth (Mammuthus primigenius)

Mammoths may have been a Sarkastodon food source.


Why Did They Die Out?

Unfortunately, there’s no clear record of why Sarkastodon died out. The fossil evidence just isn’t robust enough to give clear timelines on the animal’s existence.

That said, there was a massive extinction event at the end of the Eocene Epoch as it transitioned into the Oligocene. There’s a really creative name for this event, too. It’s called “The Eocene-Oligocene Extinction Event.”

Paleontologists and geologists aren’t always known for their wordplay.

This period was marked by drastic changes to the climate, affecting mostly marine life but doing a number on the herbivore population through a reduction in the quantity of plant life. Naturally, this diminished the livelihoods of carnivores because their food was in short supply.

This extinction event is thought to be the last breath of the Creodonts, including our furry dog-beaver-cat-bear, Sarkastodon.

What’s The Significance of Sarkastodon? 

You might be wondering why this animal is important when set against the vast array of other interesting pre-historic animals. For researchers, S. mongoliensis and S. henanensis provide a glimpse into an entirely unique set of apex predators

These large individuals might well have lived right alongside bears and tigers if their geological era were to have panned out differently. Imagine you could go to the zoo to see the descendants of Sarkastodon after walking past the bear and tiger exhibits. 

The Creodont order is special in that it’s one of the few orders of mammals that have gone completely extinct, leaving us to wonder what life would have been like if they were still here. These monsters could have occupied a similar place to Cave Bears (Short-Faced Bears) in their ecosystems. 

Ancient humans crossing the land bridge and making their way to North America encountered these bears, and there’s even some evidence that they even worshiped them. If things were different, Sarkastodon might not have given way to humans crossing Beringia, preventing them from making the same migrations that shape our modern world. 

It’s true that there are plenty of extinct species that spark our imaginations. Sarkastodon is special, though, because there’s nothing like it on earth for us to draw comparisons to. Further, the world might not have been as forgiving to humans if the Creodonts persisted through the ages!

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Frequently Asked Questions

1. Is Sarkastodon a Bear?

While Sarkastodon was as large or larger than bears, it wasn’t related to them. Sarkastodon was a Creodont, whereas bears are Carnivorans.

2. How Big Was a Sarkastodon?

A Sarkastodon individual might have weighed upwards of 1,800 pounds and stood a whopping 2.5 meters tall, not including the length of its tail.

3. When Did Sarkastodon live?

Sarkastodon lived in the middle-t0-late Eocene. That places them on earth some 37 to 50 million years ago in what are now Mongolia and China.

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About the Author

Hi! I'm Max and I'm a writer from Minneapolis, Minnesota. I've been freelancing for more than five years and love the freedom and variety that this profession offers. Animals are also a big part of my life, and a lot of my time is dedicated to playing with my cat, Herbie.

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