Qeybtan hoose ka eeg kadibna ka jawaab su'aasha afka la midka ah: Qeybtan: Sauropterygians-kii ugu horreeyay wuxuu soo muuqday qiyaastii 245 milyan oo sano ka hor (Ma), bilowgii xilligii Triassic: Sauropterygian-kii ugu horreeyay oo leh xogta saxda ah ee saxda ah wuxuu ku yaalaa qeybinta Spathian ee xilligii Olenekian ee Koonfurta Shiinaha. Tusaalooyinka hore waxay ahaayeen kuwo yaryar (qiyaastii 60 cm), xayawaanno u eg libaaxyo u eg libaaxyo leh xubno dhaadheer (pachypleurosaurs), laakiin waxay si dhakhso leh u koray dhowr mitir oo dherer ah waxayna ku faafeen biyaha dhuuban (nothosaurs).
plesiosaurs-yada madaxa yar leh ee qoorta dheer leh, iyo pliosaurs-yada madaxa weyn leh ee qoorta gaaban leh