Definition of thecodont in English:



  • A fossil quadrupedal or partly bipedal reptile of the Triassic period, having teeth fixed in sockets in the jaw. Thecodonts are ancestral to the dinosaurs and other archosaurs.

    Order Thecodontia, subdivision Archosauria

    • ‘Towards the end of the Triassic, several new and more advanced archosaur groups evolved from the thecodonts.’
    • ‘Ornithosuchus itself was originally considered a ‘pseudosuchian thecodont,’ then reclassified as an early theropod dinosaur, then later as a dinosaur uncle, and is now considered to be a side-branch on the line to crocodiles.’
    • ‘When I was a kid growing up, my books on dinosaurs, when describing the Triassic period, featured drawings and descriptions of small bipedal thecodonts, looking like miniature theropod dinosaurs.’
    • ‘Paleontologists Dingus and Rowe linked the dinosaur ancestry of birds with the origin of flight from the ground up, and the thecodont (basal archosaur) hypothesis with the origin of flight from the trees down.’
    • ‘Critics of the theropod hypotheses usually advocate a thecodont origin of birds, an aerodynamic origin of feathers, and an arboreal origin of flight.’
    • ‘Minimally, this specimen proves that the most featherlike structures in a non-avian Mesozoic vertebrate are found in a late Triassic basal archosaur, a thecodont.’
    • ‘The Triassic thecodonts had given rise to the dinosaurs and pterosaurs in the late Triassic, and these now gave rise to an extraordinary range of adaptations to new habitats.’
    • ‘All are members of the Family Proterosuchidae, which were apparently the only thecodonts of this time.’
    • ‘While it was believed that dinosaurs and pterosaurs derived from the thecodonts, no one had a good idea of where the divergence had occurred.’


Mid 19th century: from modern Latin Thecodontia, from Greek thēkē ‘case’ + odous, odont- ‘tooth’.