Triassic Period, 250-200 million years B.P. Aplete fossil Keichousaurus hui in a rectangular matrix. 2.6 kg, 32 cm (12 1/2 in.). Xingyi, Guizhou, China. Acquired 1950s-1960s. Bristol paleontological collection. Keichousaurus was a late-Triassic marine reptile, and a member of the Pleurosaur family, and went extinct 250 million years ago during the Triassic-Jurassic extinction event. They were specialised fish eaters, and were highly unusual amongst marine reptiles in that they gave birth to live young rather than laying eggs.