Wani irin fasali da ke akwai don ilimin ilmin lissafi, wanda duk dabbobi masu shayarwa masu rai (gami da monotremes), amma ba a cikin kowane farkon Triassic therapsids, an nuna shi a 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 ƙunshi articular (ƙaramin kashi a bayan ƙananan jaw) da kuma quadrate (ƙaramin kashi a bayan ƙananan jaw). Dukkanin tetrapods marasa shayarwa suna amfani da wannan tsarin ciki har da amphibians, turtles, lizards, maciji, crocodilians, dinosaur (ciki har da mammals), ichthyosaurs, pterosaurs da therapsids. Amma dabbobi masu shayarwa suna da haɗin gwiwa daban-daban, wanda ya ƙunshi ƙananan jaw (ƙananan jaw), wanda ya ƙunshi squamous squamosus, da kuma sauran dabbobi masu shayarwa. A cikin wani labarin da aka rubuta a 1981 da Kenneth A.
ƙuƙwalwa