. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. primitive or ancestral, two-legged posture —a very marked trend in the dinosaurs. Only in the persistently carnivorous thero- pods was the purely two-footed pose of the thecodonts retained. In all of the other saurischians and ornithischians there was a definite drifting away from the ancestral carnivorous mode of life, and from the bi- pedal pose. The sauropods and most of the ornithischian dinosaurs became large plant- eaters. A big bulky animal would be at an obvious disadvantage in attempting to car
. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. primitive or ancestral, two-legged posture —a very marked trend in the dinosaurs. Only in the persistently carnivorous thero- pods was the purely two-footed pose of the thecodonts retained. In all of the other saurischians and ornithischians there was a definite drifting away from the ancestral carnivorous mode of life, and from the bi- pedal pose. The sauropods and most of the ornithischian dinosaurs became large plant- eaters. A big bulky animal would be at an obvious disadvantage in attempting to carry himself about on two legs; consequently these dinosaurs came down on all fours. But it must be remembered that this was a secondary return to the primary four-footed pose, and this can be seen because the front Some Details of Dinosaurian Structure and Relationships SAURISCHIA ORNITHISCHIA theropods. yornlthopods X stegosaurs ceratopsians ankylc Primitive reptiles losaurs y The small theropod dinosaur Ornitholestes, represented in the act of catching the first known bird, Archaeopteryx. Its food probably consisted mostly, however, of other small reptiles, eggs, insects, and the like. Ornitholestes preserved many of the features of the ancestral dinosaurs. From animals similar to this the great carnivores and sauro- pods evolved Restoration by Charles R. Knight. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Colbert, Edwin H. (Edwin Harris), 1905-2001; Germann, John C. New York, N. Y. : American Museum of Natural History
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Keywords: ., bookcentury1900, bookpublishernewyork, booksubjectreptilesfossil
