The lineage of mammals and their therapsid ancestors is highlighted above in white going back to Archaeothyris and extending through Ophiacodon, Biarmosuchus, Eotitanosuchus, Scymnognathus, Aelurognathus, Procynosuchus, Thrinaxodon, Chiniquodon, Pachygenelus, Megazostrodon and Eomaia. Click on the various links for more information.
The main trends in this lineage include retention of the canine, expansion of the lateral temporal fenestra, evolution of the posterior jaw bones into ear ossicles, enlargement and posterior expansion of the dentary and a sharp reduction in overall size with Pachygenelus. The entire reptile tree is here. |