They were persistent and presumably hunted in packs: These and other features are reflected in the genome of the scimitar cats, researchers report. These are representatives of the group of saber-toothed cats that once roamed through Ice Age Europe. Analyzes of the reconstructed genome of a scimitar cat preserved in permafrost also show that these predators apparently formed quite large populations and were only distantly related to the modern representatives of cats.
The literally protruding fangs are their trademark: the saber-toothed cats belong to the prominence of the Ice Age megafauna. The most successful genus of this group was Homotherium. These predators, also known as scimitar cats, were represented on five continents and roamed the earth in the Pleistocene for millions of years. At the end of the last ice age, however, they died out together with Mammut and Co.
From research on the fossils of the Homotherium saber-toothed cats, it is known that they were about the size of lions, with powerful forelegs, and sloping backs and short tails. They also showed the typical dagger-like canine teeth, which were not quite as long as in the genus Smilodon, which is only common in America. Presumably even our ancestors in Europe encountered Homotherium and possibly had to fear their claws and teeth: Fossil finds suggest that the Scimitar cats were still present on our continent 28,000 years ago.
Paleontology from the genetic laboratory
In order to gain information about extinct creatures, scientists today no longer only use the characteristics of fossil body structures – genetics has found its way into paleontology. In some cases it is possible to coax well-preserved remains from the DNA of the former living being. The researchers led by Michael Westbury from the University of Copenhagen have now also succeeded in the case of a homotherium fossil that has survived for at least 47,500 years in Canada’s permafrost. They used modern genetic sequencing techniques to reconstruct the genome of the animal, which they assign to the species Homotherium latidens. They were then able to analyze the genetic material and compare it with other genomes. Modern genetics can now link certain genetic characteristics with the physical and cognitive abilities of living things. So it was now possible to draw conclusions about some properties of homotherium.
As the researchers report, the comparative genome analyzes uncovered signatures of an adaptation of genes that are linked to physical and cognitive performance. The characteristics suggest that these big cats had extremely strong bones and very efficient cardiovascular and respiratory systems. This reflects that they were probably very persistent in the hunt. Other genetic features indicate that their visual system was adapted to daylight. In addition, the researchers found parallels in the genetic material of Homotherium to today’s animals, which show complex social behavior. On the basis of these results, the researchers now suspect: “These big cats hunted in packs during the day and chased their prey to exhaustion,” says Westbury.
Relationships are emerging
As for the family relationships of the Homotherium saber-toothed cats, the results showed that they were only very distantly related to the modern cats. Their lines of development therefore split up about 22.5 million years ago. For comparison: The human line of development separated from the ancestors of the gibbons 15 to 20 million years ago. As the researchers further report, their genetic analysis also revealed that the homotherium saber-toothed cats were genetically very diverse compared to modern species. “It is known that this trait is linked to how many of a particular species exist. We therefore suspect that there were many of these big cats back then. That seems plausible when you consider that their fossils were found on every continent except Australia and Antarctica, ”says Westbury.
In conclusion, the researchers also comment on the question of why the Homotherium saber-toothed cats could not survive to this day despite their apparently great success. According to them, they may have specialized more in hunting large prey than other types of cats. When the populations of the large animals declined at the end of the last Ice Age, they could therefore eventually succumb to competition from the more flexible predators, write Westbury and his colleagues.
Source: University of Copenhagen, Article: Current Biology, doi: 10.1016 / j.cub.2020.09.051