File:The structure and life of birds (1895) (14563984947).jpg

Identifier: structurelifeofb00head (find matches)
Title: The structure and life of birds
Year: 1895 (1890s)
Authors: Headley, F. W. (Frederick Webb), 1856-1919
Subjects: Birds -- Anatomy Evolution
Publisher: London and New York, Macmillan and co.
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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d tothe tail, was more like a bats wing than a birds. Buthere again there is an important difference. All thebats digits except the thumb help to support the wing,in the pterodactyl only this one ulnar finger. We must, therefore, look for other evidence of thekinship of pterodactyls to birds. Take the head first.The pterodactyl had a large brain case and, for areptile, an extraordinarily high forehead. The orbitsof his eyes were large. The bones of his skull werelight and became fused together at an early age. iv CONNECTING LINKS 47 His teeth, as I have explained above, do not separatehim from the bird. In fact, it is far more a birdshead than a reptiles. Proceeding now to the longbones we find that many of them have a veryremarkable feature ; they have undoubted air cavities.These two points—the birdlike character of the skull,and the aeration of the bones—are, I think, the mostimportant of all. When they are combined with powerof flight we can infer from them other characters of
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Fig. 18.—Pterodactyl, Rhamphorhyncus phyllurus restored (after Marsh). which no direct evidence is obtainable, and principallythis—the pterodactyl must have been a warm-bloodedanimal. Flight requires great vigour such as is notfound in any cold-blooded creature. Flying-fish canhardly be said to fly, nor can the so-called FlyingDragon. Its wings are merely parachutes. Moreoverno animal that we know of combines a highly-developedbrain with cold blood. Among existing animals, birds,who on the average have a decidedly higher tem-perature than mammals, have, very many of them,pneumatic bones. It is true that the same tendencyto pneumaticity is found in the bones of the Dinosaurs 48 THE STRUCTURE AND LIFE OF BIRDS chap. of which I shall speak soon. But these also may havebeen to some extent warm-blooded. The fact that existing reptiles are cold-blooded,while birds have high temperatures, is really no barrierbetween the two classes. There was once a Pythonat the Zoological Gardens which

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