. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. no other standard will suffice. For instance, it is a common misconception to suppose that dinosaurs were all huge reptiles, carry- ing their heads high in the clouds, and borne on stout legs having the general di- mensions of small redwood trees. Nothing could be more erroneous. Some of the di- nosaurs were large, but others were very small. Indeed, there are some dinosaur skeletons that are hardly more than a foot in length; otheis are no larger than rabbits or turkeys. But given the structural patter
. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. no other standard will suffice. For instance, it is a common misconception to suppose that dinosaurs were all huge reptiles, carry- ing their heads high in the clouds, and borne on stout legs having the general di- mensions of small redwood trees. Nothing could be more erroneous. Some of the di- nosaurs were large, but others were very small. Indeed, there are some dinosaur skeletons that are hardly more than a foot in length; otheis are no larger than rabbits or turkeys. But given the structural pattern, the pattern that was established in the Triassic thecodonts, the saurischian and ornithischian dinosaurs can all be ade- quately defined and the picture of dino- saurian evolution limned. This picture in simplified form is given in the chart on the following page. It is a picture in which we see the perfec- tion and modification of the basic thecodont plan, the plan which had for its foundation a two-footed posture, a deep, light skull, and a carnivorous diet, with all of the im- plications of hunting and rapid movement imposed by such a diet and by such a mode of life. Two trends are to be seen in the develop- ment of saurischian and ornithischian adap- tations from a thecodont ancestry. One of these was the general trend towards an increase in size. The ancestral thecodonts were small reptiles; manv of the later dino- saurs were comparatively largeâthough this is not invariably the case. The other was the trend towards a modification of the. rischia. On the right is that oi the Orni- thischia, which resembled the pelvis in birds Drawing! by Johr < ' â â â â â â â â â â â â j. 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; Knight, Charles Robe
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Keywords: ., bookauthoramericanmu, bookcentury1900, booksubjectreptilesfossil
