Welcome to the MedLibrary.org Wikipedia Supplement on Dinocephalia -- Please Click to Return to Front Page

This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (April 2007)

Dinocephalia Fossil range: 270–260 Ma PreЄ Є O S D C P T J K Pg N Middle - Late Permian
Titanophoneus, a carnivorous dinocephalian of the Middle Permian
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Synapsida Order: Therapsida Suborder: Dinocephalia Seeley, 1895
Groups
see Taxonomy

Dinocephalia are a clade of large early therapsids that flourished during the Middle Permian, but became extinct leaving no descendants.

Apart from the Biarmosuchia and the Eotitanosuchidae, the Dinocephalia are the least advanced among the therapsids, although still uniquely specialised in their own way. They retain a number of primitive characteristics (e.g. no secondary palate, small 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 carnivorous, herbivorous, and omnivorous forms, some semi-aquatic and some fully terrestrial, and were also among the largest animals of the Permian period; only the biggest Caseidae and Pareiasauridea rivalling or even exceeding them in size.

All dinocephalians are distinguished by having interlocking incisors allowing a shearing contact between upper and lower teeth. In more advanced forms, the heels on the lingual sides of the incisor teeth met to form a crushing surface when the jaws were shut, allowing the grinding up of plant matter.

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.

Dinocephalians are extraordinary for their large size. The biggest herbivores (Tapinocephalus) and omnivores (Titanosuchus), may have massed up to two tonnes in weight, and were some 4.5 meters long, while the largest carnivores (such as Titanophoneus and Anteosaurus) were at least as long, with heavy skulls 80 cm long, and overall weights of around half a tonne.

Evolutionary history

The dinocephalians evolved from a pelycosaur-like therapsid that lived in the late Cisuralian epoch. These animals radiated at the expense of the dying pelycosaurs, who dominated during the early part of the Permian. During the early Capitanian, advanced dinocephalia 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. Shortly after, at the height of their diversity, the dinocephalians suddenly died out. The reason for their extinction is not clear. They were replaced by much smaller Therapsids: herbivorous Dicynodontia and carnivorous biarmosuchians, Gorgonopsians and Therocephalians.

Taxonomy

Head of Stenocybus.

Struthiocephalus.

Niaftasuchus.

Little recent research has been done into dinocephalian relationships. The following arrangement therefore should be taken as provisional only.

• CLASS SYNAPSIDA
  • Order THERAPSIDA
    • Suborder DINOCEPHALIA
      • ? Rhopalodon
      • ? Family Phreatosuchidae
        • Phreatosuchus
        • Phreatosaurus
      • Family Estemmenosuchidae
        • Estemmenosuchus
          • Estemmenosuchus uralensis
          • Estemmenosuchus mirabilis
      • Stenocybus
      • Anteosauria
        • Family Brithopodidae / Anteosauridae
          • Brithopus
          • Family Syodontidae
            • Syodon
            • Australosyodon
          • Deuterosaurus
          • Titanophoneus
          • Subfamily Anteosaurinae (or Tribe Anteosaurini)
            • Anteosaurus
            • Doliosauriscus
      • Tapinocephalia
        • Styracocephalus
        • Family Titanosuchidae
          • Titanosuchus
          • Jonkeria
        • Family Tapinocephalidae
          • Tapinocanius
          • Ulemosaurus
          • Moschops
          • Struthiocephalus
          • Tapinocephalus

More information

National Dinosaur Museum's "Dinosaur Age" Issue 18

See also

• Evolution of mammals
• Permian tetrapods

References

This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. (December 2006)

External links

• Dinocephalia - Palaeos

Wikipedia content modification information:

• This page was last modified on 28 October 2008, at 23:39.

Wikipedia Authorship and Review

Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.

Wikipedia Usage Guidelines

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Dinocephalia".

The URL for this specific entry is:

• http://medlibrary.org/medwiki/Dinocephalia

All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.