“Nothing like this has existed before in mammals,” say the authors of a new study
If we think of felines , one of the first features that come to mind is their sharp fangs. However, this is a consequence of evolution and about 42 million years ago, their ancestors were very different. Now, a new study published in the journal ‘ PeerJ ‘ places a predator from the west coast of North America as the first hypercarnivore or mammal that only ate meat.
“Today, the ability to eat an exclusively carnivorous diet is not uncommon. Tigers do it, polar bears can do it. If you have a domestic cat, you may even have a hypercarnivore at home. But 42 million years ago , mammals were starting to figure out how to survive on meat alone,” says paleontologist Ashley Poust of the San Diego Museum of Natural History.
“One big advance was developing specialized teeth for cutting meat, which is something we see in this newly described specimen.”
Although it has been in the museum’s collection since 1988, it has not been analyzed until now. Called Diegoaelurus vanvalkenburghae , only a part of the lower jaw is preserved with some teeth, just the ones that show a lot of information about what that cat-like predator that inhabited North America was like millions of years ago. D. vanvalkenburghae is part of the extinct feline subfamily called Machaeroidinae, meaning ‘dagger-like’. This fossil appears to be the most recent piece found and is very different from its closest known relative, Apataelurus kayi .
“Nothing like this has existed before in mammals,” says Post. Some mammalian ancestors had long tusks, but Diegoaelurus and it’s few relatives represent the first feline approach to a meat diet, with saber teeth at the front and sharp scissor teeth called carnassials at the back. It’s a powerful combination that various groups of animals have evolved independently from millions of years ago to now.”
It is important to note that other Machaeroidinae subfamilies also evolved saber-toothed predators, including Smilodon fatalis , the most famous saber-toothed.
The fossil was unearthed from a bedrock of the Santiago Formation, in San Diego (USA). This formation dates back to the late Eocene and can give us information about a time when the world was warmer. “Fossils from the Santiago Formation show us a wet, forested California where tiny rhinoceroses, primitive tapirs, and strange sheep-like herbivores grazed under the trees while unusual primates and marsupials clung to the canopy above,” says Post. “This richness of prey species would have been a smorgasbord for Diegoaelurus, allowing it to live the life of a specialized hunter earlier than most other mammals.”
For now, this is the only fossil of Diegoaelurus, if the researchers hope to find more similar pieces and be able to continue delving into the history of the first carnivorous feline in history.
