Fossils have been found in the Cynognathus Assemblage Zone of the Beaufort Group in South Africa and the Omingonde Formation of Namibia, dating back to the Early and Middle Triassic.

[4][5] A bony secondary palate and precise postcanine tooth occlusion are seen as derived characteristics in Trirachodon that are similar to those of mammals.

Three other specimens were later referred to T. kannemeyeri, which was distinguished from the type on the basis of snout length and number of postcanine teeth.

Another species of Trirachodon called T. angustifrons was named in 1946 from a narrow skull found in Tanzania, but this material was later proven to be from the traversodontid Scalenodon.

There have been many suggested reasons for this behavior in Trirachodon, including protection from predation, sites for reproduction and or rearing young, and thermoregulation.

Recent studies in the bone histology of many specimens of Trirachodon have led to an increased understanding of the ontogeny and lifestyle of these animals.