Dinocephalia

Source: Wikipedia, the free encyclopedia.
For other uses, see Dinocephalia (disambiguation).

Dinocephalia
Temporal range:
Ma
Restoration of two
genera of dinocephalians : Titanophoneus (an anteosaur) devouring a Ulemosaurus (a tapinocephalian
).
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade:
Therapsida
Suborder: †Dinocephalia
Seeley, 1894
Subgroups

See Taxonomy

Dinocephalians (terrible heads) are a

omnivorous forms.[3] Many species had thickened skulls with many knobs and bony projections. Dinocephalians were the first non-mammalian therapsids to be scientifically described[4] and their fossils are known from Russia, China, Brazil, South Africa, Zimbabwe, and Tanzania.[5][6]

Description

Life restoration of Moschops capensis
Skull of Titanophoneus

Apart from the

dentary) shared with their pelycosaur ancestors, although they are also more advanced in possessing therapsid adaptations like the expansion of the ilium
and more erect limbs.

They include

omnivorous forms. Some, like Keratocephalus, Moschops, Struthiocephalus and Jonkeria were semiaquatic, others, like Anteosaurus, were more terrestrial.[7]

Dinocephalians were among the largest animals of the

Pareiasauridea
reaching them in size.

Size

Dinocephalians were generally large. The biggest herbivores (Tapinocephalus) and omnivores (Titanosuchus) may have massed up to 2 tonnes (4,400 lb), and were some 4.5 metres (15 ft) long, while the largest carnivores (such as Titanophoneus and Anteosaurus) were at least as long, with heavy skulls 80 centimetres (31 in) long, and overall masses of around a half-tonne.

Skull

All dinocephalians are distinguished by the interlocking incisor (front) teeth. Correlated features are the distinctly downturned facial region, a deep temporal region, and forwardly rotated suspensorium. Shearing contact between the upper and lower teeth (allowing food to be more easily sliced into small bits for digestion) is achieved through keeping a fixed quadrate and a hinge-like movement at the jaw articulation. The lower teeth are inclined forward, and occlusion is achieved by the interlocking of the incisors. The later dinocephalians improved on this system by developing heels on the lingual sides of the incisor teeth that met against one another to form a crushing surface when the jaws were shut.

Most dinocephalians also developed pachyostosis of the bones in the skull, which seems to have been an adaptation for intra-specific behaviour (head-butting), perhaps for territory or a mate. In some types, such as Estemmenosuchus and Styracocephalus, there are also horn-like structures, which evolved independently in each case.

Evolutionary history

 
Anteosauria
    

Anteosauridae

 Tapinocephalia 
 
   

Estemmenosuchidae

 
 

Styracocephalidae


 
Phylogeny of Dinocephalia following Fraser-King et al. 2019[8]

The dinocephalians are an ancient group and their ancestry is not clear. It is assumed that they must have evolved during the earlier part of the

brithopodids
of the Russian Ocher fauna, were already a diverse group of herbivores and carnivores.

During the Wordian and early Capitanian, advanced dinocephalians radiated into a large number of herbivorous forms, representing a diverse megafauna. This is well known from the Tapinocephalus Assemblage Zone of the Southern African Karoo.

At the height of their diversity (middle or late

Dicynodontia and carnivorous Biarmosuchians, Gorgonopsians and Therocephalians
.

Taxonomy

estemmenosuchid
Anteosaurus, an anteosaur
Ulemosaurus, a tapinocephalian

See also

References

  1. ^ Day, Michael O.; Guven, Saniye; Abdala, Fernando; Jirah, Sifelani; Rubidge, Bruce; Almond, John (2015). "Youngest dinocephalian fossils extend the Tapinocephalus Zone, Karoo Basin, South Africa". South African Journal of Science. 111: 1–5.
  2. ^ "Driveria". Fossilworks.
  3. doi:10.1111/j.1502-3931.2009.00171.x
    .
  4. doi:10.1080/14772019.2010.492645
    .
  5. doi:10.1007/s12052-009-0117-4
    .
  6. S2CID 131447562
    .
  7. doi:10.1002/spp2.1411.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  8. ^ Fraser-King, Simon W.; Benoit, Julien; Day, Michael O.; Rubidge, Bruce S. (2019). "Cranial morphology and phylogenetic relationship of the enigmatic dinocephalian Styracocephalus platyrhynchus from the Karoo Supergroup, South Africa". Palaeontologia Africana. 54: 14–29.

Further reading

  • Carroll, R.L. (1988). Vertebrate Paleontology and Evolution. W.H. Freeman.

External links

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