Matsayi: Wata alama da ke samuwa ga ilimin ilmin lissafi, wanda duk dabbobi masu shayarwa masu rai (ciki har da monotremes), amma ba a cikin kowane farkon Triassic therapsids ba, an nuna shi a cikin Hoto na 1 (a dama), wato: dabbobi masu shayarwa suna amfani da kasusuwa biyu don jin cewa duk sauran amniotes suna amfani da su don cin abinci. A farkon amniotes suna da haɗin gwiwa na jaw wanda ya kunshi articular (ƙaramin kashi a bayan ƙananan jaw) da kuma quadrate (ƙaramin kashi a baya na babba jaw). Dukkanin tetrapods marasa shayarwa suna amfani da wannan tsarin ciki har da amphibians, turtles, lizards, maciji, crocodilians, dinosaur (ciki har da mammoth), ichthyosaurs, pterosaurs da therapsids. Amma dabbobi masu shayarwa suna da haɗin gwiwa daban-daban, wanda ya kunshi ƙananan jaw (ƙananan jaw), wanda ya ƙunshi squibs, squibs na amniotes da sauran dabbobi masu shayarwa suna amfani da su don cin abinci.
dentary (ƙashin jaw na ƙasa, wanda ke ɗauke da hakora) da squamosal