Tritylodont

Phylogeny

Because of their mammal-like appearance, tritylodontids were originally placed within Mammalia. Starting with the work of British paleontologist D.M.S. Watson in 1942, a close relationship was favored between tritylodontids and cynodonts. Watson and other paleontologists noted that tritylodontids lacked the dentary and squamosal jaw articulation that was characteristic of early mammals. Haughton & Brink (1954) were the first to classify tritylodontids within Cynodontia. Later studies identified close similarities between the teeth of tritylodontids and traversodontids, and tritylodontids were eventually thought to be descendants of traversodontids. Under this classification, which was widely accepted in the following decades, Tritylodontidae was previous considered to be part of Gomphodontia, a larger group within Cynognathia. The name Tritylodontoidea was previously used for the group, which traditionally included the families Diademodontidae, Trirachodontidae, Traversodontidae, and Tritylodontidae.