泥盆纪箅鱼 Placoderms(盾皮鱼类) Figure Il-62 The Devonian placoderm Bothriolepis
泥盆纪沟鳞鱼 Placoderms（盾皮鱼类）
Devonian lungfish The Devonian crossopterygian lungfish Eusthenopteron had sturdy fins whose struc- ture foreshadowed that of four footed land animals that were to be their descendents (St. Louis Science Center diorama
肺鱼(lungfish) 总鳍鱼（crossopterygian) Devonian lungfish
鱼石螈(D3C1)最早原始两牺类 amphibian QS59998S0nE Figure 1 1-73 The skeleton of Ichthyostega still retains the fishlike form of its cros sopterygian ancestors (From H. L. Levin. Life Through Time. Dubuque, lowa, william C Brown Co., 1975)
鱼石螈(D3 -C1 )—最早原始两栖类 amphibian
迷齿类 迷齿构造原总 始鳍 Labyrinthodont 两鱼 总鳍鱼类 Opercular bones 栖类的比较 鱼类 P Circumorbital bones 两栖类 avity Tooth-bearing bones 一类肉鳍鱼亚纲与 Figure 12-33 Similarity between the crossopterygians phibian(right); shading identifies the bones(u= ulna, r and the earliest amphibians. a. Similanity of skeleton. b. radius, h= humerus) that the two groups have in common mparison of skulls and lower jaws of a crossopterygian d, Comparison of cross sections of showing the com- (left) and an ichthyostegid amphibian(right). Shading identi- plex structure found in both the crossopterygians(left)and fies the bones the two skulls have in common. c Compari- amphibians(right) son of the limb bones of a crossopterygian(left) and am-
总鳍鱼类( 肉鳍鱼亚纲) 与 原始两栖类的比较 迷齿类 总鳍鱼类 迷齿构造 鱼类 两栖类
引螈(两栖美) 4n> Figure 11-74 The large Permian amphibian Eryops. (Length is about 2 meters
引螈（两栖类）—二叠纪