Homotherini Temporal range: | |
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Skeleton of Homotherium serum from Friesenhahn cave, Texas Memorial Museum, University of Texas at Austin, Austin, Texas | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Carnivora |
Suborder: | Feliformia |
Family: | Felidae |
Subfamily: | † Machairodontinae |
Tribe: | † Homotherini Fabrini, 1890 |
Genera | |
Homotherini is a tribe (or subtribe) [1] of saber-toothed cats of the family Felidae (true cats). The tribe is commonly known as scimitar-toothed cats. These saber-toothed cats were endemic to North America, Europe, Asia, Africa, and South America [2] from the Miocene to Pleistocene living from c. 23 Ma until c. 12,000 years ago. [3]
Compared to the usually massively built dirk-toothed phenotype, apparent in Smilodon , Megantereon and the feliform Barbourofelis (just to list a few), their upper canines were smaller than those of equally sized cats of that phenotype, but they had serrated edges. [4] [5] The scimitar-toothed phenotype has also evolved independently in other mammal families. [6]
Based on mitochondrial DNA sequences extracted from fossils, the lineage of Homotherium is estimated to have diverged from that of Smilodon about 18 Ma ago. [7]
The scimitar tooth form was used to assist in the hunting of herbivorous megafauna. With its hyper sharp and serrated form it was perfect for ripping flesh off of downed prey. However, if this tooth would come into contact with bone it could get caught, serrations worn off, or even completely broken thus leaving the organism without a food source, leading to starvation and death. [8] [9]
There is a debate about how both the scimitar-tooth and the dirk-tooth evolved in felines and other mammals. the two sides of the debate revolve around whether it was derived from a sexual dimorphic trait or if it was completely natural selection that drove the creation of these phenotypes. The argument for sexual dimorphic origins stems from the fact that in mammals sexual dimorphic traits manifest as tools for males to compete for females. It is believed that the scimitar-tooth and the dirk-tooth were originally only in males for use in competition but then with the rise of mega-herbivores it became favorable for females to take up the trait as well. [10] The natural selection side of the debate argues that the scimitar and dirk-tooth both evolved because of the unfilled niche of predation of megaherbivores so the trait evolved to take advantage of said niche. [11]
Genus | Species | Image |
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† Amphimachairodus Kretzoi, 1929 |
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† Homotherium Fabrini, 1890 |
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† Lokotunjailurus Werdelin 2003 |
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† Nimravides Kitts 1958 |
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† Xenosmilus Martin et al., 2000 |
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The phylogenetic relationships of Homotherini are shown in the following cladogram: [12] [13] [14] [15] [16]
†Homotherini |
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Machairodus is a genus of large machairodont or ''saber-toothed cat'' that lived in Africa, Eurasia and North America during the late Miocene. It is the animal from which the subfamily Machairodontinae gets its name and has since become a wastebasket taxon over the years as many genera of sabertooth cat have been and are still occasionally lumped into it.
Dinofelis is an extinct genus of machairodontine, usually classified in the tribe Metailurini. It was widespread in Europe, Asia, Africa and North America from 5 million to about 1.2 million years ago. Fossils very similar to Dinofelis from Lothagam range back to around 8 million years ago, in the Late Miocene.
Smilodon is a genus of felids belonging to the extinct subfamily Machairodontinae. It is one of the best known saber-toothed predators and prehistoric mammals. Although commonly known as the saber-toothed tiger, it was not closely related to the tiger or other modern cats. Smilodon lived in the Americas during the Pleistocene epoch. The genus was named in 1842 based on fossils from Brazil; the generic name means "scalpel" or "two-edged knife" combined with "tooth". Three species are recognized today: S. gracilis, S. fatalis, and S. populator. The two latter species were probably descended from S. gracilis, which itself probably evolved from Megantereon. The hundreds of specimens obtained from the La Brea Tar Pits in Los Angeles constitute the largest collection of Smilodon fossils.
Homotherium is an extinct genus of machairodontine scimitar-toothed cat that inhabited North America, South America, Eurasia, and Africa during the Pliocene and Pleistocene epochs from around 4 million to 12,000 years ago. In comparison to Smilodon, the canines of Homotherium were shorter, and it was probably adapted to running down rather than ambushing prey.
A saber-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.
Nimravidae is an extinct family of carnivorans, sometimes known as false saber-toothed cats, whose fossils are found in North America and Eurasia. Not considered to belong to the true cats, the nimravids are generally considered closely related and classified as a distinct family in the suborder Feliformia. Fossils have been dated from the Middle Eocene through the Late Miocene epochs, spanning about 33.2 million years.
Machairodontinae is an extinct subfamily of carnivoran mammals of the family Felidae. They were found in Asia, Africa, North America, South America, and Europe from the Miocene to the Pleistocene, living from about 16 million until about 10,000 years ago.
Metailurini is an extinct taxonomic tribe of large saber-toothed cats that lived in Africa, Asia, Europe, and North America from the Miocene to the Pleistocene.
Smilodontini is an extinct tribe within the Machairodontinae or "saber-toothed cat" subfamily of the Felidae. The tribe is also known as the "dirk-toothed cats". They were endemic to South America, North America, Europe, Asia, and Africa during the Miocene to Pleistocene, from 10.3 mya—11,000 years ago, existing for approximately 10.3 million years.
Paramachaerodus is an extinct genus of saber-tooth cat of the subfamily Machairodontinae, which was endemic to Europe and Asia during the Middle and Late Miocene from 15 to 9 Ma. A 2022 phylogenetic analysis suggested that the genus may be polyphyletic.
Xenosmilus is an extinct genus of homotherin machairodontine that was discovered in Florida in 2001. It has one species, Xenosmilus hodsonae.
Thylacosmilus is an extinct genus of saber-toothed metatherian mammals that inhabited South America from the Late Miocene to Pliocene epochs. Though Thylacosmilus looks similar to the "saber-toothed cats", it was not a felid, like the well-known North American Smilodon, but a sparassodont, a group closely related to marsupials, and only superficially resembled other saber-toothed mammals due to convergent evolution. A 2005 study found that the bite forces of Thylacosmilus and Smilodon were low, which indicates the killing-techniques of saber-toothed animals differed from those of extant species. Remains of Thylacosmilus have been found primarily in Catamarca, Entre Ríos, and La Pampa Provinces in northern Argentina.
Megantereon is an extinct genus of prehistoric machairodontine saber-toothed cat that lived in North America, Eurasia, and Africa. It is closely related to and possibly the ancestor of Smilodon.
Adelphailurus is an extinct genus of metailurin machairodontine (saber-toothed) cat that inhabited western North America during the middle Pliocene. It is monotypic, containing only the species Adelphailurus kansensis.
Barbourofelidae is an extinct family of carnivorans of the suborder Feliformia, sometimes known as false saber-toothed cats, that lived in North America, Eurasia and Africa during the Miocene epoch and existed for about 7.9 million years. Thought to be an independent lineage from the Nimravidae and Machairodontinae, which had all attained elongated canines, recent research argues that it may be a subfamily of the Nimravidae, extending its biochronological range into the Miocene, although this issue is not yet fully resolved.
Nimravides is a genus of extinct saber-toothed cats that lived in North America during the Late Miocene, between 10.3 and 5.332 Ma. Despite its scientific name, Nimravides does not belong to the Nimravidae, but is a true cat belonging to the family Felidae.
Lokotunjailurus is an extinct genus of saber-toothed cats (Machairodontinae) which existed during the late Miocene and earliest Pliocene epoch and is known from localities in northern, central, eastern and southern Africa. A big cat, it was more slender than comparable recent species and its build suggests cursoriality. It is grouped among a group of similar-looking saber-toothed cats known as the scimitar-tooths.
Lars Werdelin is a Swedish paleontologist specializing in the evolution of mammalian carnivores. His areas of scientific interest include the evolutionary interaction of carnivores and hominins in Africa, as well as the evolution and phylogeny of carnivore clades such as the Machairodontinae, the lynxes and the Hyaenidae.
Amphimachairodus is an extinct genus of large machairodonts. It is also a member of the tribe Homotherini within Machairodontinae and is most closely related to such species as Xenosmilus, Homotherium itself, and Nimravides. It inhabited Eurasia, Northern Africa and North America during the late Miocene epoch.
Taowu is an extinct genus of machairodonts, a type of saber-toothed cat. It lived during the Early Pleistocene about 2.5 million years ago in East Asia. So far, only one skull is known, found in northern China. Based on this, a relatively small representative of the saber-toothed cats can be reconstructed, which only reached the size of a present-day leopard. In its dentition characteristics, it mediates between phylogenetic older forms such as Amphimachairodus and younger members such as Homotherium. The genus was scientifically described in 2022, but the find material was recovered as early as the 1930s.