Therocephalia

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Therocephalia
Moschorhinus

Moschorhinus

Temporal occurrence
Middle Perm to Middle Triassic
268 to 237 million years
Locations
  • southern africa
  • Russia
  • China
  • Antarctic
Systematics
Amniotes (Amniota)
Synapsids (Synapsida)
Therapsids (Therapsida)
Theriodontia
Eutheriodontia
Therocephalia
Scientific name
Therocephalia
Broom , 1905

The Therocephalia are an extinct group of terrestrial vertebrates from the group of Therapsiden ("mammal-like reptiles"). They first appeared in South Africa's fossil deposits from the Middle Permian . They were most rich in shape in Upper Perm, from which there are finds from southern Africa, Russia and China. They became rarer in the Triassic . There are finds from the Lower and Middle Triassic of the Antarctic.

The Therocephalia were large, mainly predatory carnivores or small insectivores. Some sub-Triassic forms, such as Bauria from South Africa, were herbivorous .

features

Skull of Bauria , drawing by Robert Broom

Therocephalic skulls were relatively large, massive, and long, but relatively low. The muzzle was broad, with large canines and simple, conical molars, which could also be missing.

The jaw muscles reached over the skull and left only a narrow sagittal ridge formed by the parietal bones between the two upward-facing windows of the skull . This is the main difference from the skulls of the Gorgonopids . Some forms of therocephalia had a fully developed secondary palate, a feature they share with the cynodonts but, as there are differences in detail, evolved independently of them. The skull window and orbit could flow together. The cheekbone was never wide.

The lumbar vertebrae had small, thin ribs. The iliac bone had finger-like extensions at its rear end. Her limbs were long. Some forms had mammalian body proportions and a severely degenerated tail. The phalangeal formula was 2.3.3.3.3 and thus corresponds to that of mammals.

Systematics

External system

The family relationships are illustrated by the following cladogram:

  Therapsids  

Tetraceratops


   

 Biarmosuchia


  Eutherapsida  

 Dinocephalia


  Neotherapsida  


 Anomodontia


  Theriodontia  

 Gorgonopsia


  Eutheriodontia  

 Therocephalia †


   

 Cynodontia 









Template: Klade / Maintenance / Style

Internal system

Kuhn gives seven families and 55 genera for Therocephalia and 9 more families and 45 genera for Bauriamorphs. The early Therocephalia were originally classified as Pristerognathidae, but later recognized as a paraphyletic group and divided into the short-snouted Lycosuchidae and the long-snouted Scylacosauridae. Another former Therocephalic family, the Scaloposauridae, were composed mainly of juvenile specimens of different genera. All further developed therocephalic forms form the taxon Eutherocephalia, including the hyena-like Whaitsiidae and the herbivorous Baurioidea.

literature

Web links

Commons : Therocephalia  - collection of images, videos and audio files

Individual evidence

  1. Bruce S. Rubidge & Christian A. Sidor: Evolutionary patterns among permo-triassic Therapsids. Annu. Rev. Ecol. Syst. 2001. 32: 449-80 Complete PDF