marine reptiles. However, only the smallest turtles survived the extinction at
the end of the Cretaceous.
Turtles are the closest living relatives of crocodiles, another extremely
successful aquatic reptile.The crocodiles,which passed through the extinction
practically unscathed,are closer to turtles than they are to lizards, snakes, and
birds. Turtles, which are holdovers from an ancient group called anapsids thatFigure 121TheChinle
Formation, Uinta Range,
Utah, where crocodile
fossils are found.
(Photo courtesy of the
author)
Figure 122The
ichthyosaur was an air-
breathing reptile that
returned to the sea.
Historical Geology