The fearsome-looking saber-toothed cat prowled across the grasslands of Europe and America in the surprisingly recent past. With many species known from the fossil record, the fanged creatures were diverse and varied, and now researchers have been peeking into this complicated evolutionary past by reconstructing sections of their ancient DNA.
An international team led by Potsdam University, Germany, has been comparing two different species of saber-toothed cat. The first belonged to the group known as Homotherium, which lived through much of Europe and North America, South America and even Africa over a period of 4 million years. The second was a member of the much more famous Smilodon genus of the Americas, which stalked the Pleistocene grasslands until around 10,000 years ago when they went extinct.
From four fossils, the researchers have been able to decode the mitochondrial DNA for two species of the toothy cat, allowing them to begin reconstructing the felines' evolutionary past. Their results, published in Cell Press, have shown, somewhat surprisingly, that the creatures have a deep evolutionary history, with the lineage that gave rise to the sabered beasts splitting off from the rest of the moggies some 20 million years ago.
But what is more surprising was the discovery that relatively quickly after this break – geologically speaking at least – the two genera went their own separate ways. The results show that the group that contains Smilodon and that which houses Homotherium diverged at least 18 million years ago, meaning that even though the two groups of saber-toothed cat look physically very similar, they are more distantly related than the modern tiger is to the domestic cat.
Included among the fossils that the team were able to reconstruct the mitochondrial genome from was that of a Homotherium cat dredged up from the North Sea. This patch of water has been rich picking for fossils from the Pleistocene, as the shallow sea was until very recently open tundra criss-crossed with rivers. Fishermen frequently bring up the remains of mammoths, woolly rhinos, and even humans.
But the Homotherium skull was more important than most. Until its discovery, dating to around 28,000 years old, most experts believed that the cats went extinct in Europe hundreds of thousands of years earlier.
“This find was so special because Homotherium is generally believed to have gone extinct in Europe around 300,000 years ago, so [this specimen is] over 200,000 years younger than the next-to-youngest Homotherium find in Europe,” explained Johanna Paijmans, who carried out the research.
This means that modern humans and Neanderthals were almost certainly living side-by-side with them, while in the Americas, humans there were also competing with Smilodon.