Almost 42 million years ago, a fearsome creature the size of a bobcat roamed the forests of what is now San Diego , United States. When this animal inhabited these borders, San Diego was covered with tropical jungles populated by many small rodents, marsupials, primates and mammals. And, unlike most animals of the time, it was a hypercarnivore, born to eat meat and almost exclusively meat.
It is Diegoaelurus vanvalkenburghae , a recently identified species of the mysterious and extinct Machaeroidine family, not closely related to present-day carnivores, believed to be the first mammals with saber-toothed tusks and sharp cutting teeth.
A creature new to science
A team of paleontologists from the San Diego Museum of Natural History (USA) has identified this new predator thanks to a 71-millimeter-long lower jaw with teeth. Examination of the fossils revealed that it had long saber-shaped canine teeth because the bony chin was down to protect the fangs and a space in the lower teeth to fit them.
According to experts, it is the first feline approach to a meat diet. “Today, the ability to eat an exclusively meat-based diet, also called hypercarnivorism , 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 just discovering how to survive on meat alone,” explains Ashley Poust, co-author of the paper published in PeerJ magazine and a researcher at the Natural History Museum (NAT) in San Diego, USA.
“A major advance was developing specialized teeth for cutting meat, which is something we see in this newly described specimen,” continues the expert. Its large fangs would have been used to bite into the throat of prey or to tear through flesh.
The fossil of the first hypercanivore
The predator’s name honors San Diego County, where the specimen was found, and scientist Blaire Van Valkenburgh, former president of the Society for Vertebrate Paleontology, whose work on the evolution of carnivores influenced this research, the authors explain. .
The fossil, housed in the San Diego Natural History Museum’s paleontology collection, offers a window into what the Earth was like during the Eocene period, more than 40 million years ago. Although this creature was much smaller than the well-known Smilodon , or saber-toothed (which appeared on Earth millions of years after D. vanvalkenburghae became extinct), they were both saber-toothed hypercarnivorous predators. Diegoaelurus vanvalkenburghae would have been a relatively new and powerful type of hunter.
“Nothing like this has existed before in mammals. Some mammalian ancestors had long tusks, but Diegoaelurus and its 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 potent combination that various groups of animals have evolved independently in the millions of years since then ,” says Poust.
The valuable fossil was recovered from an Oceanside construction site by the museum’s PaleoServices team . And, according to the researchers, this hypercarnivore could have coexisted with other saber-toothed animals.
“Fossils from the Santiago Formation show us a wet, forested California where tiny rhinoceroses, primitive tapirs, and strange sheep-like herbivores oreodonts grazed under the trees while unusual primates and marsupials clung to the canopy above. This wealth 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 ,” the expert concludes.
Referencia: Zack, et al. “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”. PeerJ, 2022
