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Scimitar-Toothed Cats hunted prey to the point of exhaustion, DNA study suggests

Artist's impression of crooked teeth chasing an old horse.

Artist’s impression of cats with crooked teeth Chasing down an old horse.
illustration:: Velizar Simeonovski / University of Copenhagen

Scientists have mapped the entire nuclear genome of a species of saber-toothed cat known as Homotherium latidens, also called the scimitar tooth cat. The resulting DNA analysis suggests that these Pleistocene predators were fearsome pack hunters, able to walk long distances while hunting their prey to the point of exhaustion.

Smilodon, With incredibly long teethis 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 latidensis also worth our attention.

Oh, in case you’re wondering, “saber-toothed cats” is a kind of slang colloquial term used to describe extinct predatory cats with long canine teeth 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 the Felidae. And no, we don’t call them “saber-toothed tigers” anymore, because they weren’t really tigers.

Homotherium, also known as the scimitar tooth cat, may not have canines in the upper jaw on the order of Smilodon, but these predators had a lot going for them. They were built for long distance running and were slimmer than Smilodon and modern lions. HomotheriumAccording to Michael Westbury, the lead author of the new study and geneticist at the University of Copenhagen, the proportions of the limbs are reminiscent of those of modern hyenas, as they have longer forelegs compared to the hind legs.

Reconstruction of Homotherium latidens.

Reconstruction of Homotherium latidens.
image:: R. Barnett et al., 2020 / Current Biology

Sit comfortably on the food web, Homotherium Hunting large Pleistocene herd animals such as giant ground sloths and mammoths. They used their long incisors and lower canines for stabbing, grasping, and picking up and relocating dead prey.

These properties and behaviors were derived mainly from fossil evidence, but many questions too Homotherium remained unanswered, such as the specific genetic adaptations that enabled them to thrive and survive, and whether these animals mingled with other saber-toothed cat species.

To learn more about cats with scimitar teeth, Westbury and colleagues obtained and analyzed DNA from a Homotherium latidens Specimen found in Yukon Territory, Canada. The sample, which was drawn from frozen sediment, was too old to be radiocarbon dating, so it is at least 47,500 years old, according to the new study. The researchers mapped the 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 these data enabled us to do a lot of interesting analyzes that are normally limited to high quality living species genomes,” Westbury said in an email, saying he was surprised to find such good quality DNA from such an old sample receive .

The scientists found no fewer than 31 genes in Homotherium that was subject to a positive selection. It is noteworthy that their nervous system genetic makeup indicates complex social behaviors, which fits well with our understanding that this animal is a pack hunter. Cats with scimitar teeth also had good vision during the day, meaning they were a diurnal species that likely hunted in daylight. They had special genetic adaptations for strong bones and robust cardiovascular and respiratory systems.

Taken together, the “novel adaptations in these genes may have enabled sustainable walking that is necessary for hunting in more open habitats and striving for prey to the point of exhaustion,” the authors wrote in the study.

“Our results support previous work attempting to correlate certain morphological and anatomical features of H. latidens his lifestyle, ”said Westbury.

Another key finding from the study is that cats with scimitar teeth were genetically different, at least when compared to modern cat species. They only bred among each other and were heavily populated when it came to big cats. This is new information for scientists.

“We think that Homotherium may have been relatively common compared to living big cats. Homotherium are relatively rare in the fossil record, which leads researchers to believe that they are not that common, ”Westbury said. “However, when we examined the genetic differences between the mother and father of our individual, we found that they are vastly different from those of other cat species, suggesting a large population size.”

Importantly, this DNA analysis was limited to a single person, so future work should try to confirm these results with more genetic evidence.

The researchers found that too Homotherium and modern cats differed from a common ancestor a very long time ago – about 22.5 million years ago. For comparison: humans and gibbons separated from a common ancestor around 15 to 20 million years ago. It should therefore come as no surprise that there are such big differences in saber-toothed cats compared to modern lions, the former appearing like a kind of bear-hyena-lion hybrid.

The new DNA study confirms findings from the fossil record and reveals a few things about it Homotherium we didn’t know before. Life had been good for these animals for millions of years, and large herd animals fueled their voracious lifestyle. With the gradual loss of large prey, it all came to an end and the end of the last ice age.

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