Temporal range: Upper Triassic – mid Cretaceous
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. 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. 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]
- named after the shape of animal's teeth, with three cusps.
- 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). 
- 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.