Rangarira ndima iri pasi apa uye ipapo pindura mubvunzo gare gare mumutauro mumwe chetewo sechikamu:  Passage: Sauropterygians yakatanga kuoneka makore angangoita mamirioni 245 apfuura (Ma), pakutanga kweTriassic nguva: sauropterygian yekutanga ine chaiyo stratigraphic datum iri mukati mechikamu cheSpathian cheOlenekian nguva muSouth China. Mienzaniso yokutanga yakanga iri miduku (inenge 60 cm), mhuka dzakafanana nemakudo dzine makumbo marefu (pachypleurosaurs), asi nokukurumidza dzakakura kuva dzinoverengeka mamita marefu ndokupararira mumvura dzisina kudzama (nothosaurs). Chiitiko chokutsakatika kweTriassic-Jurassic chakavaparadza vose kunze kweve plesiosaurs. Mukati meJurassic yekutanga, idzi dzakapatsanuka nekukurumidza kuva plesiosaurs refu-yemutsipa-yemusoro mudiki chaiwo, uye mapfupi-yemutsipa-yemusoro mukuru-yemusoro pliosaurs. Pakutanga, zvaifungidzirwa kuti plesiosaurs ne pliosaurs dzaiva mhuri huru mbiri dzakaparadzana idzo dzakatevera nzira dzakasiana dzokuchinja. Zvinoita sokuti idzi dzaingova morphotypes pakuti marudzi acho maviri akachinja kakawanda, mamwe pliosaurs achibva kumadzitateguru e plesiosaur, uye zvimwewo.  Mubvunzo: Mukati meJurassic yapakuvamba, pliosaurs yakakamurwa kuva mapoka api maviri?
plesiosaurs chaiyo ine mitsipa mirefu ine misoro miduku, uye pliosaurs ine mitsipa mipfupi ine misoro mikuru