Theriodontia
Theriodonts | |
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Restoration of three genus of the theriodont clade: Cynodontia ).
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Synapsida |
Clade: | Therapsida |
Clade: | Theriodontia Owen, 1876 |
Groups | |
The theriodonts (
Naming
In 1876, Richard Owen named a suborder Theriodontia, which he divided into the Cynodontia and the Gomphodontia.[1]
The modern
Evolution
Theriodonts appeared at the same time as their
Early theriodonts may have been
Eutheriodontia
Eutheriodontia refers to all theriodonts except the gorgonopsians (the most "primitive" group). They included the therocephalians and the cynodonts. The cynodonts include the mammals. The eutheriodonts have larger skulls, accommodating larger brains and improved jaw muscles.
The eutheriodontian theriodonts are one of the two synapsid survivors of the great Permian–Triassic extinction event, the other being the dicynodonts. Therocephalians included both carnivorous and herbivorous forms; both died out after the Early Triassic. The remaining theriodonts, the cynodonts, also included carnivores, such as Cynognathus, as well as newly evolved herbivores (Traversodontidae). While traversodontids for the most part remained medium-sized to reasonably large (the length of the largest species was up to two meters), the carnivorous forms became progressively smaller as the Triassic progressed. They "miniaturised". By the Late Triassic, the small cynodonts included the rodent-like Tritylodontidae (possibly related to or descended from traversodontids), and the tiny, shrew-like, Tritheledontidae, related to the Mammaliaformes. The tritheledontids died out during the Jurassic, and the tritylodontids survived into the Cretaceous, but their relatives, the mammals, continued to evolve. Many mammal groups managed to survive the Cretaceous–Paleogene extinction event, which wiped out the non-avian dinosaurs, allowing the mammals to diversify and dominate the Earth.
Taxonomy
Classification
- Order Therapsida
- Theriodont *
- Suborder †Gorgonopsia
- Family †Gorgonopsidae
- Family †
- Eutheriodontia
- Suborder †Therocephalia
- Family †Lycosuchidae
- (unranked) †Scylacosauria
- Family †Scylacosauridae
- Infraorder †Eutherocephalia
- Family †Hofmeyriidae
- Family †Moschorhinidae
- Family †Whaitsiidae
- Superfamily †Baurioidea
- Family †Bauriidae
- Family †Ericiolacteridae
- Family †Ictidosuchidae
- Genus †Ictidosuchoides
- Genus †Ictidosuchus
- Family †Ictidosuchopsidae
- Family †Lycideopidae
- Suborder Cynodontia
- Suborder †Therocephalia
- Suborder †Gorgonopsia
- Theriodont *
Phylogenetics of Theriodontia
- Therapsida
- †Biarmosuchia
- †Eotitanosuchia
- †Dinocephalia
- †Anomodontia
- Theriodontia
- †Gorgonopsia
- †Therocephalia
- Cynodontia
- †Dviniidae
- Mammalia
- †Procynosuchidae
- †Galesauridae
- †Thrinaxodontidae
- †Cynognathidae
- †Gomphodontia
- †Chiniquodontidae
- †Probainognathidae
- †Tritheledontidae (Ictidosauria)
- †
See also
- Evolution of mammals
- Anomodonts
- Timeline of evolution
Notes
- teeth
References
External links
- Theriodontia - at Paleos