Triconodonta

Triconodonta is an extinct order of synapsids, a group of mammals-like reptiles that lived during the Permian and Triassic periods, approximately 299 to 201 million years ago. The name "Triconodonta" comes from the Greek words "tri" meaning three, "kono" meaning horn, and "odon" meaning tooth, referring to the three horn-like structures on the skull of some species. Triconodonta is further divided into two suborders: Therocephalia and Anomodontia.

Therocephalia, the more basal suborder, includes forms like Dromasaurus and Therocephalus. They had a more reptilian appearance, with a long, narrow snout and a single horn on the skull. Anomodontia, on the other hand, is more diverse and includes forms like Anomocephalus and Triceratops. Anomodonts had a broader, more robust skull with multiple horns and a more mammal-like appearance.

Triconodonta played a significant role in the evolution of mammals. They were one of the last groups of synapsids to go extinct during the Permian-Triassic extinction event, which is thought to have been caused by a combination of volcanic activity, climate change, and asteroid impact. The extinction of Triconodonta paved the way for the radiation of mammals in the Triassic period.