 Of the large marine reptiles, only sea turtles were left; and of the non-marine large reptiles, only the semi-aquatic crocodiles and broadly similar choristoderes survived the extinction, with the latter becoming extinct in the Miocene.Of the great host of dinosaurs dominating the Mesozoic, only the small beaked birds survived.This dramatic extinction pattern at the end of the Mesozoic led into the Cenozoic.