New Saber-Tooth Species With Specialized Teeth For Tearing Off Flesh Discovered, Will Shed Light on the Evolution of Carnivorous Mammals

First Mammal to Live as a Successful Hypercarnivore

The fossil that paleontologists found in 1988 at a construction site in Oceanside, California, was of a lower jaw of a cat-like animal believed to be 42 million years old. Scientific American reported that the team used modern techniques and found that the mammal belonged to a previously unknown machaeroidine, one of the five other now-extinct saber-toothed predators.

It had enlarged upper canines estimated to be about two to three inches long. The creature most likely preyed on small and medium-sized mammals. Study co-author Ashley Poust from the Museum noted that the fossil was similar to its fellow machaeroidines, although its jaw, the size of its teeth and the spacing between stood out.

He added that Diegoaelurus seems to have figured out how to live as the first successful hypercarnivore mammal whose diet is 70% meat, like modern cats, lions, and polar bears. Study co-author Shawn Zack explains that the abundance of prey may have led the Diegoaelurus to have evolved teeth that could process meat very efficiently that it gradually lost the ability to break other foods.

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Representing An Evolutionary Experiment

According to Mirage News, the early meat-eating predator and its relatives represent a sort of evolutionary experiment of how the first hypercarnivore lived and evolved to modern cats. The machaeroidines are poorly understood because of the lack of fossil specimens, with only a handful from Wyoming and Asia. Scientists were not sure whether multiple species lived in the same period.

Zack said that analysis of the fossils revealed that machaeroidines were more diverse than initially thought. Previously, they identified a large saber-tooth form called Apataelurus that lived in eastern Utah. The recent study found that the smaller form approximately lived at almost the same time, raising the possibility that there were more species during that period waiting to be discovered.

Additionally, Poust said that this overlapping existence points a striking distance in the time when the next cat-like animals appeared in North America, like the nimravids or saber-tooth false cats. If ever these groups coexisted, could they have competed for space and prey? Poust said that they do not know yet, but they hope to find the answers as they find more evidence in San Diego, which is surprisingly an essential place for carnivore evolution.

They described the newly discovered saber-tooth predator in their study, titled "Diegoaelurus, a New Machaeroidine (Oxyaenidae) From the Santiago Formation (Late Uintan) Of Southern California and the Relationships of Machaeroidinae, the Oldest Group of Sabertooth Mammals," which was published in the journal PeerJ. The 3D view of the jaw fossil can now be accessed through the Museum's website.

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