Le plus ancien fossile attribué à Therapsida serait Tetraceratops insignis -LRB- Lower Permian -RRB-, M. Laurin & R.R. Reisz, 1996, The osteology and relationships ofTetraceratops insignis, the oldest known therapsid, Journal of Vertebrate Paleontology 16 -LRB- / O1 / O-RRB- : 95 -102 J. Liu, B. Rubidge & J. Li, New basal synapsid supports Laurasian origin for therapsids, 2009, Acta Palaeontol.
Paléontologie des vertébrés.