Scientists have mapped the entire nuclear genome of a saber-toothed cat species known as Homotherium latidens, also called the scimitar-toothed cat. The resulting DNA analysis suggests these Pleistocene predators were fearsome pack hunters capable of running for long distances as they chased their prey to exhaustion.
Smilodon, with its impossibly long fangs, is probably the most famous saber-toothed cat, but new research published today in Current Biology suggests another saber-toothed cat, a species known as Homotherium latidens, is equally worthy of our attention.
Oh, in case you’re wondering, “saber-toothed cats” is a kind of colloquial catch-all term used to describe extinct predatory felids with long canines that protruded from their mouths even when their jaws were closed. The more technical term for this group is Machairodontinae, a now-extinct subfamily of Felidae. And no, we don’t call them “saber-toothed tigers” anymore, because they weren’t actually tigers.
Homotherium, also known as the scimitar-toothed cat, may not have sprouted maxillary canines on the scale of Smilodon, but these predators had a lot going for them. They were built for long-distance running and were more slender than Smilodon and modern lions. Homotherium’s limb proportions are reminiscent of those seen on modern hyenas, as they featured longer forelimbs relative to their hindlimbs, according to Michael Westbury, the lead author of the new study and a geneticist at the University of Copenhagen.
Sitting comfortably atop the food web, Homotherium preyed on large Pleistocene herd animals, such as giant ground sloths and mammoths. They used their long incisors and lower canines for puncturing and gripping, as well as picking up and relocating dead prey.
These traits and behaviors were primarily inferred from fossil evidence, but many questions about Homotherium remained unanswered, such as the specific genetic adaptations that allowed them to thrive and survive and whether these animals interbred with other saber-toothed cat species.
To learn more about scimitar-toothed cats, Westbury and his colleagues recovered and analyzed DNA from a Homotherium latidens specimen found in Canada’s Yukon Territory. The specimen, pulled from frozen sediment, was too old for radiocarbon dating, so it’s at least 47,500 years old, according to the new study. The researchers mapped its entire nuclear genome—a first for a saber-toothed cat—and compared it to those of modern cats, like lions and tigers.
“The quality of this data allowed us to do a lot of interesting analyses that are normally limited to high-quality genomes from living species,” explained Westbury in an email, saying he was surprised to obtain such good quality DNA from a specimen so old.
The scientists found no less than 31 genes in Homotherium that were subject to positive selection. Of note, the genetic makeup of their nervous system points to complex social behaviors, which meshes nicely with our understanding