Duba wurin da ke ƙasa sannan ka amsa tambayar daga baya a cikin harshe ɗaya kamar yadda wurin yake:  Passage: Wani irin wannan fasalin da ke akwai don ilimin kimiyyar halittu, wanda dukkan dabbobi masu shayarwa masu rai (gami da monotremes), amma ba a cikin kowane farkon Triassic therapsids, an nuna shi a cikin Hoto na 1 (a dama), wato: dabbobi masu shayarwa suna amfani da kasusuwa biyu don ji cewa duk sauran amniotes suna amfani da su don cin abinci. Tsoffin amniotes suna da haɗin gwiwa na jaw wanda ya ƙunshi haɗin gwiwa (ƙaramin kashi a bayan ƙananan jaw) da kuma murabba'i (ƙaramin kashi a bayan babba jaw). Dukkanin tetrapods da ba masu shayarwa ba suna amfani da wannan tsarin ciki har da amphibians, turtles, lizards, macizai, crocodilians, dinosaur (ciki har da tsuntsaye), ichthyosaurs, pterosaurs da therapsids. Amma dabbobi masu shayarwa suna da haɗin haƙarƙarin da ya bambanta, wanda ya ƙunshi ƙashin haƙarƙarin ƙananan haƙarƙarin, wanda ke ɗauke da haƙoran) da kuma ƙashin ƙugu (wani ƙaramin ƙashin kwanyar). A cikin Jurassic, kwarangwal da kasusuwa na kasusuwa sun samo asali a cikin incus da malleus kasusuwa a tsakiyar kunne. Dabbobi masu shayarwa kuma suna da condyle occipital biyu; suna da kusoshi biyu a gindin kwanyar da suka dace a cikin kashin wuya na sama, yayin da sauran tetrapods suna da condyle occipital guda daya. A cikin wata kasida ta 1981, Kenneth A. Kermack da abokan aikinsa sun yi jayayya don zana layin tsakanin dabbobi masu shayarwa da farkon synapsids a wurin da aka samo tsarin dabbobi masu shayarwa na ɓoyewa da kuma haɗin gwiwar hakori. Ka'idar da aka zaɓa, in ji su, batun sauƙi ne kawai; zaɓinsu ya dangana ne a kan gaskiyar cewa "ƙashin jaw shine mafi kusantar kashi na ƙashin ƙashin dabba mai shayarwa na Mesozoic da za a adana". A yau, yawancin masana kimiyyar halittu suna la'akari da cewa dabbobi dabbobi ne idan sun cika wannan ka'ida.  Tambaya: Wane irin haɗin Jaw ne farkon amniotes ke da shi?
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