Otu ihe dị otú ahụ dị maka paleontology, nke ụmụ anụmanụ niile dị ndụ (gụnyere monotremes), ma ọ bụghị nke ọ bụla n'ime mmalite Triassic therapsids, egosiri na Figure 1 (n'aka nri), ya bụ: ụmụ anụmanụ na-eji ọkpụkpụ abụọ maka ịnụ ihe na ndị ọzọ niile amniotes na-eji maka iri nri. Ndị mbụ amniotes nwere nkwonkwo agba nke mejupụtara articular (obere ọkpụkpụ dị n'azụ agba ala) na quadrate (obere ọkpụkpụ dị n'azụ agba elu). Ndị niile na-abụghị mammal tetrapods na-eji usoro a gụnyere amphibians, turtles, lizards, agwọ, crocodilians, dinosaurs (gụnyere mammal), ichthyosaurs, pterosaurs na therapsids.
dentary (ọkpụkpụ nke ala jaw, nke na-ebu ezé) na squamosal