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Temporal range: Upper Triassic – mid Cretaceous
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Synapsida
Order: Therapsida
Suborder: Cynodontia
Infraorder: Eucynodontia
(unranked): Cynognathia
Family: Tritylodontidae
Cope, 1884

Tritylodonts [1] were small to medium-sized mammal-like cynodonts.

They were the last family of the non-mammalian synapsids. One of the last cynodont lines to appear, the family Tritylodontidae descended from a Cynognathus-like cynodont.

The Tritylodonts were herbivorous, chewing through vegetation, such as stems, leaves, and roots.

They were the longest surviving of all the non-mammalian therapsids. They appeared in the latest Triassic period, and persisted through the Jurassic until the middle of the Cretaceous.[2] This shows that the Tritylodonts were a successful group of therapsids, even though they lived right beneath the ruling dinosaurs' feet, so to speak.

Chronoperates from the Palaeocene, after the Cretaceous and the K/T extinction event, may be a Tritylodont. If so, then the Tritylodonts were elusive and rare during the Upper Cretaceous, because no Tritylodonts were found by that time. However, the Chronoperates's anatomy also closely resembles to that of symmetrodonts – a mammalian lineage.

It is very clear that the Tritylodonts were warm-blooded.[3] The Tritylodont fossils were found in the Americas, South Africa, and Eurasia. They may have managed to live worldwide, including Antarctica.

References[change | edit source]

  1. named after the shape of animal's teeth, with three cusps.
  2. Ruta M; Botha-Brink J; Mitchell S.A. & Benton M.J. 2013. The radiation of cynodonts and the ground plan of mammalian morphological diversity. Proceedings of the Royal Society B: Biological Sciences 280 (1769). [1]
  3. Hopson JA. 2012. The role of foraging mode in the origin of therapsids: implications for the origin of mammalian endothermy. In Studies in vertebrate paleobiology: essays in honor of John R. Bolt, eds Lombard R.E. et al pp. 126–148. Fieldiana: Life and Earth Sciences 5. Chicago, IL: The Field Museum of Natural History.