Epilogue : What Conies of Studying Vertebrates 



superimposed upon them, the groups fall into line i 

 as in the anatomic series. 



in the same order 



Paleontology arranges the vertebrates in a chronologic series 

 depending on the distribution of vertebrate fossils in geologic strata. 

 Fishes appear in the early Paleozoic (see Table 3, p. 411). In the mid- 

 Paleozoic Devonian, an "Age of Fishes," are found the first evidences 

 of amphibians. Reptiles appear in the later Paleozoic. Mammal-like 

 reptiles toward the close of the Paleozoic are succeeded by definitely 

 mammalian types in the middle Mesozoic (Jurassic). Archaeopteryx, 

 the earliest known bird, was Jurassic. 



Anatomy, Embryology, and Paleontology, each using only its 

 own data, arrange the major groups of vertebrates in the same serial 



Fig. 601. Phytogeny of the vertebrates. The varying width of the black bands 

 representing the several groups suggests the relative abundance of the members 

 of the groups. (Courtesy, Romer: "Vertebrate Paleontology," University of 

 Chicago Press.) 



