The Late Triassic Record of Cynodonts: Time of Innovations in the Mammalian Lineage

摘要: The Triassic period witnessed a great diversification of lineages, recovering from one the worst extinction events known in Earth’s history. Therapsids, lineage that includes mammals as only living members, enjoyed remarkable success during Triassic. This clade Late Permian to Early Cretaceous non-mammaliaform cynodonts, represented by paraphyletic array taxa successively more closely related mammaliaforms (considered basal several palaeontologists). In Middle Triassic, cynodonts are numerous thrived mostly Gondwana, whereas taxon, Nanogomphodon, has been registered Laurasia. Cynodont diversity this time interval is mainly composed gomphodonts, featuring bucco-lingually expanded postcanines, members their sister-group, sectorial-toothed probainognathians, very scarce. On contrary, Jurassic most abundant Laurasia (although also present Gondwana) and particularly tritheledontids ubiquitous herbivorous tritylodontids. thus constitutes pivotal lapse, marked an expansion geographical distribution cynodonts. During time, cynodont assemblages include representatives old new lineages first documented. contribution presents review geographic summarizes main morphologies lineage, including Mammaliaformes, key group our understanding early evolution mammals.