File:The American Museum journal (c1900-(1918)) (17972169458).jpg

Title: The American Museum journal
Identifier: americanmuseumjo16amer (find matches)
Year: c1900-(1918) (c190s)
Authors: American Museum of Natural History
Subjects: Natural history
Publisher: New York : American Museum of Natural History
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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THE BEGINNINGS OF FLIGHT 9 flight. Just such tufts of feathers are known to have occurred in Archceoptcryx (BerUn specimen), and Mr. Beebe con- chides that, Uke the back fins of the fly- ing fish, they served to support the hinder part of the botly as the creature sailed — or as our Enghsh cousins prefer to put it — parachuted through the air. For Mr. Beebe doubts that even Archoeop- teryx was capable of true flight, believing that the fore limbs, like the hind, were rigidly extended at right angles to the body and not flapped. A most striking bit of e\idence is the fact that just as o\-erlapping co^•erts are found above the secondaries of the bird's wing and alternately with them, so the bristle-like quills on the thigh of the pigeon are surmounted l)y a series of quills placed precisely like the wing coverts.
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A later stage when there has begun a shortening; iif the tail and concentration of the tail feathers The value of any character or piece of evidence does not lie in its size but in its constanc^', or in its apparent relation to other characters, so these little bristle- like feathers of the nestling dove, accord- ing to Mr. Beebe, hint at a time when, as just noted, the;s' ser\ed a useful pur- pose and were sufficiently developed to support, or help support, the hinder por- tion of the body. At this stage in the development of birds, which shoukl be somewhere near the lower Jurassic, about seven million years ago, both fore and hind limbs bore feathers; but neither pair of limbs took an active part in aerial locomotion, their fmiction being that of planes, purely passive. This phase of the development Mr. Beebe terms the Tdrapteryx or four-winged stage. At this stage, to quote from Mr. Beebe, "flight was merely gliding, the fingers were too free, the arm bones too delicate, the sternum small or absent, and these facts considered in connection with the small, weak pehis, make it impossible to picture the creature as flying skillfully about. In succeeding generations the pelvic wings would be- come more and more reduced. Having arisen from among the surrounding scales, they had for a time volplaned through the air of early ages, a structure passive and, as future centuries would show, of merely transitory function. Yet they were of tremendous impor- tance in allowing the pectoral scales to develop, to become feathers, and then to assume an importance which was to make the class of birds supreme in the air. Yet the function of the pelvic wings had been so passive and negative that no special muscling had been neces- sary, no increase or coalescence of bony

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