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.
Among the earliest animals that can be described as "sabertooths" are the gorgonopsids, a group of non-mammalian therapsids that lived during the Middle-Late Permian, around 270-252 million years ago.
Instead, many members are classified into different families of Feliformia, such as Barbourofelidae and Nimravidae;[5] 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.
Evidence from the numbers found at the La Brea Tar Pits suggests that Smilodon, like modern lions, was a social carnivore.
[8] The first saber-tooths to appear were non-mammalian synapsids, such as the gorgonopsids; they were one of the first groups of animals within Synapsida to experience the specialization of saber teeth, and many had long canines.
Several defining characteristics are a lack of a coronoid process, many sharp "premolars" more akin to pegs than scissors, and very long skulls.
At least one genus, Lotheridium, possessed long canines, and given both the predatory habits of the clade as well as the generally incomplete material, this may have been a more widespread adaptation.
The best-known barbourofelid is the eponymous Barbourofelis, which differs from most machairodonts by having a much heavier and more stout mandible, smaller orbits, massive and almost knobby flanges, and canines that are farther back.
The evolution of enlarged canines in Tertiary carnivores was a result of large mammals being the source of prey for saber-toothed predators.
For the saber-tooth, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than "megaherbivores" as previously believed.
Brain, the saber-tooth would use a "downward thrust of the head, powered by the neck muscles" to drive the large upper canines into the prey.
Meehan et al.[12] note that it took around 8 million years for a new type of saber-toothed cat to fill the niche of an extinct predecessor in a similar ecological role; this has happened at least four times with different families of animals developing this adaptation.
Although the adaptation of the saber-like canines made these creatures successful, it seems that the shift to obligate carnivorism, along with co-evolution with large prey animals, led the saber-toothed cats of each time period to extinction.
Dinictis felina Pogonodon platycopis Eusmilus olsontau Eusmilus villebramarensis Eusmilus cerebralis Hoplophoneus dakotensis Hoplophoneus primaevus Hoplophoneus occidentalis Nanosmilus kurténi Eofelis edwardsii Nimravus brachyops Haplogale media Barbourofelis morrisi Barbourofelis fricki Barbourofelis loveorum Barbourofelis whitfordi Sansanosmilus vallesiensis Proailurus lemanensis Hyperailuricitis skinneri Nimravides pedionomus Nimravides thinobates Hyperailuricitis intrepidus Hyperailuricitis validus Pseudaelurus quadridentatus Machairodus aphanistus Machairodus horribilis Amphimachairodus kurteni Amphimachairodus kabir Amphimachairodus giganteus Lokotunjailurus emageritus Dinobastis serus Dinobastis venezuelensis Xenosmilus hodsonae Homotherium latidens Dinofelis petteri Dinofelis paleoonca Dinofelis cristata Metailurus major Metailurus parvulus Promegantereon ogygia Megantereon whitei Megantereon cultridens Megantereon ekidoit Megantereon hesperus Smilodon fatalis Smilodon populator Smilodon gracilis Styriofelis lorteti Styriofelis turnauensis Felinae sensu lato (includes all extant pantherines and felines) All saber-toothed mammals lived between 33.7 million and 9,000 years ago, but the evolutionary lines that led to the various saber-tooth genera started to diverge much earlier.
