This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 edition. Excerpt: ...and have left no descendants. The Mammal-Like Reptiles (Cynodonts).--Another remarkable group of Permian reptiles which appears to have been purely African in distribution was a group of mammal-like reptiles, called Cynodontia, believed by the authorities to have given rise to the line from which the ...
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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 edition. Excerpt: ...and have left no descendants. The Mammal-Like Reptiles (Cynodonts).--Another remarkable group of Permian reptiles which appears to have been purely African in distribution was a group of mammal-like reptiles, called Cynodontia, believed by the authorities to have given rise to the line from which the mammals arose. These cynodonts (dog-toothed reptiles) showed many tendencies toward mammalian conditions, chief among which were: hcterodont dentition (a specialization of the teeth into incisors, canines and molars), more effective types of limbs for rapid land locomotion, a tendency for the angulare and articulare bones of the lower jaw to disappear, and a tendency for the skull to become completely roofed over and for the so-called vacuities to disappear. These cynodonts were evidently carnivorous types of which Cynognathus (Fig. 123, E) is a good example. The head of another cynodont, Scymnognathus (Fig. 123, F) shows clearly the dog-like dentition. These reptiles are once more to claim our attention when we come to discuss the question of the origin of mammals. There is reason to believe that at least five or six other reptilian orders had representatives in the Permian or Permo-Carboniferous: Chelonia (turtle's), plesiosaurs (aquatic reptiles), ichthyosaurs (fishlike reptiles), Squamata (primitive lizards), Rhynchocephalia (beaked reptiles), and Parasuchia (primitive crocodiles). Possibly also the great order of dinosaurs had its beginnings in the Permo-Carbonifcrous, though as yet there is no direct evidence of their presence during this period. A number of orders of reptiles not only had their origin during the Palaeozoic, but actually ran out their entire course of specialization and became entirely extinct before the Mesozoic age...
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Seller's Description:
Good. Good hardcover. No DJ. Text contains underlining/marking throughout. Writing on end papers and inside covers. Covers show light edge wear with rubbing/light scuffing. Spine edge wear. Binding cracked but still intact.; 100% Satisfaction Guaranteed! Ships same or next business day!
