The Tritheledontidae or tritheledontids, also known as ictidosaurs, were small to medium-sized (about 10 or 20 cm long) cynodonts. They were extremely mammal-like, highly specialized cynodonts, although they still retained a very few reptilian anatomical traits. Tritheledontids were mainly carnivorous or insectivorous, though some species may have developed omnivorous traits. Their skeletons show that they had a close relationship to mammals. Tritheledontids or their closest relatives may have given rise to primitive mammals. The tritheledontids were one of the longest lived non-mammalian therapsid lineages, living from late Triassic to the Jurassic period. Tritheledontids became extinct in the Jurassic period, possibly due to competition with prehistoric mammals such as the triconodonts.