. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. Primitive Reptiles â e have seen how the amphibians \A/ arose, reached the culmination of B their evolutionary development and for a geologically brief period enjoyed a certain degree of dominance among the animals living on the land. We have seen how this culmination and dominance of the amphibians was attained by the late Paleo- zoic labyrinthodonts, the giants, and in y~ many ways the most highly evolved of these primitive land vertebrates. The labyrinthodonts, in spite of their evolutionary progress
. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. Primitive Reptiles â e have seen how the amphibians \A/ arose, reached the culmination of B their evolutionary development and for a geologically brief period enjoyed a certain degree of dominance among the animals living on the land. We have seen how this culmination and dominance of the amphibians was attained by the late Paleo- zoic labyrinthodonts, the giants, and in y~ many ways the most highly evolved of these primitive land vertebrates. The labyrinthodonts, in spite of their evolutionary progress, were unable to evolve to any great eminence because at an early stage in their history they suffered from the competition of other land verte- brates that were better adapted to a terrestrial environment than they were. These were the reptiles, the cold-blooded land animals in which the young develops directly without any tadpole stage. The reptiles arose soon after the appear- ance of the labyrinthodonts and developed side by side with them. By Permian times there was actually a certain amount of "pushing and shoving" between the reptiles and the amphibians for elbow room upon the surface of the land. But the amphibians lost the battle; the last of the labyrintho- donts retreated once again to the primitive home for all life, the water, there to enjoy a brief respite of existence before they finally became extinct, while the reptiles, ever evolving and increasing, reached hith- erto unsealed heights in the climb up the evolutionary ladder. f Why did the amphibians lose the evolu- tionary race to the reptiles? The answer probably is to be found in one word, repro- duction. The reptiles prevailed because in them a new method of perpetuating the species had evolved. It is probable that the labyrinthodont amphibians had to return to the water for the laying of the eggs, just as is the case with most of the amphibians of the present day. In the early reptiles, how- eve
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Keywords: ., bookauthoramericanmu, bookcentury1900, booksubjectreptilesfossil
