Cynodont

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{{Taxobox | color = pink | name = Cynodonts | From: Late Permian | regnum = Animalia | phylum = Chordata | classis = Synapsida | ordo = Therapsida | subordo = Cynodontia | subordo_authority = Owen, 1861 | subdivision_ranks = Families | subdivision = See text }}

Cynodonta, or 'dog teeth', were one of the most diverse groups of therapsids. Their teeth were fully differentiated, the braincase bulged at the back of the head, and many of them walked in an upright manner unlike other reptiles. Cynodonts still laid eggs, as all Mesozoic proto-mammals probably did. They also were among the groups which survived the Permian mass extinction. The most derived cynodonts are found within Eucynodontia clade, which also contains the members of Mammalia.

The mammal-like structure of Cynodonts hints that all mammals have descended from a single group of cynodonts. Representative genera include the large carnivorous cynognathids, equally large herbivorous traversodonts, and small and mammal-like tritylodontids and ictidosaurs. It is likely that Cynodonts were at least partially if not completely warm-blooded, covered with hair, which would have insulated them and helped to maintain a high body temperature.

During their evolution, cynodonts changed their teeth from being designed for catching and holding prey and then swallowing whole, to adding specialized teeth, including molars, designed for better mastication of food allowing for quicker digestion. Additionally, the jaw of the cynodonts reduced the number of jaw bones. This freed up the superfluous bones to evolve into an entirely new function, becoming parts of the mammal's inner ear.

Improved hearing gave these creatures a better awareness of their environment and, in turn, this increasing sensitivity called for a greater capacity for processing the auditory information in the brain. Cynodonts also developed a secondary palate in the roof of the mouth. This allowed air to flow to the lungs through the back of the mouth, allowing cynodonts to chew and breathe at the same time. This characteristic is present in all mammals.

1 Taxonomy
2 See also
3 References
4 External links

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Taxonomy

Order Therapsida
- Suborder CYNODONTIA
  - Family Diviniidae
  - Family Procynosuchidae
  - Epicynodontia
    - Family Galesauridae
    - Family Thrinaxodontidae
      - Thrinaxodon
    - Infraorder Eucynodontia
      - Family Cynognathidae
      - Family Tritylodontidae
        Oligokyphus
        Tritylodon
      - Probainognathia
        Ecteninion
        Family Chiniquodontidae
        Family Probainognathidae
        Family Trithelodontidae
        Mammaliaformes

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References

Hopson, J.A. & J.W. Kitching (2001). "A probainognathian cynodont from South Africa and the phylogeny of non-mammalian cynodonts." Bull. Mus. Comp. Zool. 156: 5-35.

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