Machairodontini is an extinct tribe of large saber-toothed cats of the subfamily Machairodontinae, that lived in Europe, Asia, Africa, and North America, during the Middle and Late Miocene.
Description
Machairodont means "knife-tooth" which perfectly describes the species that make up Machairodontini. These predators are related to extant cats, the Felinae, and share a common ancestor within the Felidae clade. Machairodontines were medium to large sized saber-toothed cats that would have reached a size rivaling today's lions, which can reach weights of over . This clade is also occasionally classified as being part of the Homotherini, and includes genera such as Machairodus, Hemimachairodus and Miomachairodus. They were first characterized by their scimitar canines in the upper jaw. This means that the canines are shorter and coarsely serrated, with vertical flattening. Although the upper canines are shorter than other more famous saber toothed cats such Smilodon, they are still abnormally long in comparison to the rest of the teeth in the mandible. There is also a space separating the canines and premolars known as a diastema. The bottom portion of the jaw contains small incisors that are in a straight row with a large, lower canine. These canines are not nearly as big as the upper canines. There is a diastema between the canines and the premolars in the lower jaw as well.
These prehistoric predators not only have long upper canine teeth but they also have elongated limb bones, which differ from the squatter legs of the other group of saber-toothed cats, the Smilodontini. Although not many complete skeletons of machairodontine species have been found, those specimens known illustrate the long limb bones and shorter tails. The tails are of medium length and do not reach the ground as they do with cats today.
Taxonomy
Machairodontini was named by Gill (1872) as well as de Beaumont (1964). It was assigned to Machairodontinae by Berta and Galiano (1983).
Classification
Phylogeny
The phylogenetic relationships of Machairodontini are shown in the following cladogram:
Geologic and geographic distribution
The earliest machairodontine is the genus Miomachairodus from the late middle Miocene in Turkey. There are also species of the Machairodontini found in Africa from the late Miocene to the early Pleistocene, in deposits such as Lothagam, Sahabi, and Langebaanweg. The Machairodontini moved East during the Vallesian (11.6-0.9 million years ago), when they entered Asia about 10 million years ago and became one of the major predators of this time.
There were once also similarities between species found in North America and Eurasia that support an immigration event from Eurasia which took place before the late Miocene, at about the end of the early Hemphillian (~5 million years ago). The Old World (Europe/Africa/Asia) species Machairodus aphanistus and the New World (North and South America) species Machairodus catocopis (now know to belong to the genus Nimravides) were once though to have been very closely related, suggesting that there was a migration and that these saber-toothed cats did radiate from Eurasia into North America. This made sense based on evolutionary similarities between North American and Eurasian species as well as the immigration of other species between these two continents at this time in Earth's history. However, this was disproven with discoveries that the Homotherini were not descended from the Machairodontini and that several species of Machairodontine, such as Nimravides catacopsis, Homotherium and Amphimachairodus were revealed to be Homotherines.