Procynosuchidae, along with Dviniidae, were the earliest cynodonts. They appeared around 260 million years ago, and were most abundant during the latest Permian time (251 mya), shortly before the Permian-Triassic extinction event. Despite being the basal member of the cynodont clade, they already showed some of the advanced mammalian characteristics, but Procynosuchids bore resemblance to the Therocephalians.