568 - Heredity and Evolution 



UWM*A^ 



Fig. 29-14. Whole skeleton of another dinosaur, Tyrannosaurus rex, from the Cretaceous strata of Hell Creek 

 Basin, Montana. (Courtesy of the American Museum of Natural History, New York.) 



The early Mesozoic strata show a great (Figs. 29-14 and 29-15), and the flying reptiles 



diversification of the reptile group, not only (pterosaurs). Also in the early Mesozoic rocks 



as to forms resembling the modern lizards, one finds the first primitive mammals. But 



turtles, snakes, and so forth, but also as to the first birds, such as the toothed and clawed 



archaic forms like the gigantic dinosaurs Arcliaeopteryx (Fig. 29-16), are not found 



Fig. 29-15. Tyrannosaurus and Triceratops, a restoration by Charles R. 

 Knight. (Courtesy of the American Museum of Natural History, New York.) 



