722 GENETICS AND EVOLUTION 



IL- 



Figure 35.2. Texas in the Permian Period, about 230,000,000 years ago. Various 

 pelycosaurs are shown. Some had large fins, others were essentially like lizards. In the 

 lower illustration is a salamander-like amphibian with a flat, triangular skull. (Copyright, 

 Chicago Natural History Museum, from the painting by Charles R. Knight.) 



