August 15, 2022
The probainognathians (Probainognathia) form one of the two main subgroups of the eucynodonts, the cynognathians being the other. They are mostly carnivorous, although some species may have evolved into omnivorous traits. The suspected oldest and most basal probainognathian known is the Middle Triassic (Anisian) Lumkuia of South Africa, although probainognathians do not become prominent until the Middle Norian stage of the Upper Triassic. Three groups survived the Triassic-Jurassic extinction: the Tritheledontidae, the Tritylodontidae (the latter having existed until the Cretaceous as shown by the genera Montirictus and Xenocretosuchus) as well as the Mammaliaformes, which would later give rise to mammals.