Saber-toothed predator

A saber-tooth (alternatively spelled sabre-tooth) is any member of various extinct groups of predatory therapsids, predominantly carnivoran mammals, that are characterized by long, curved saber-shaped canine teeth which protruded from the mouth when closed. Saber-toothed mammals have been found almost worldwide from the Eocene epoch to the end of the Pleistocene epoch (42 million years ago – 11,000 years ago).^[1][2][3]

One of the best-known genera is the machairodont or "saber-toothed cat" Smilodon, the species of which, especially S. fatalis, are popularly referred to as "saber-toothed tigers", although they are not closely related to tigers (Panthera). Despite some similarities, not all saber-tooths are closely related to saber-toothed cats or felids in-general. Instead, many members are classified into different families of Feliformia, such as Barbourofelidae and Nimravidae;^[4] the oxyaenid "creodont" genera Machaeroides and Apataelurus; and two extinct lineages of metatherian mammals, the thylacosmilids of Sparassodonta, and deltatheroideans, which are more closely related to marsupials. In this regard, these saber-toothed mammals can be viewed as examples of convergent evolution.^[5] This convergence is remarkable due not only to the development of elongated canines, but also a suite of other characteristics, such as a wide gape and bulky forelimbs, which is so consistent that it has been termed the "saber-tooth suite."^[6]

Of the feliform lineages, the family Nimravidae is the oldest, entering the landscape around 42 mya and becoming extinct by 7.2 mya. Barbourofelidae entered around 16.9 mya and were extinct by 9 mya. These two would have shared some habitats.