File:A history of birds (1910) (14563066719).jpg

Identifier: historyofbirds00pycr (find matches)
Title: A history of birds
Year: 1910 (1910s)
Authors: Pycraft, W. P. (William Plane), 1868-1942
Subjects: Birds
Publisher: London, Methuen and Co
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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tines, it shouldbe noted, have become relatively smaller than in Rhea. Somuch for these three stages in brief outline. Now compare any, or all three, of these palates with thoseof, say, a Gull and a Common Fowl. For clearness sake letthe comparison be made with the skull of the Fowl (111. 14).One of the first things to be noted will be the greatly reducedsize of the vomer, which indeed is now little more than a vestige.It will next be noted that this reduced vomer has lost all rela-tion with the pterygoid, and is borne by an ingrowing pair ofplates from the palatines. These, moreover, it will be noticed,have now greatly changed, both in their relative position as wellas in length and shape. Compared with those of Rhea and theTinamous, they will be found to have extended forwards in theform of a pair of slender rods, wedged in between the palatine 44 A HISTORY OF BIRDS process of the premaxilla and the maxillo-palatine processes,in this last matter resembhng the Tinamous. Finally, they
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III. 14.—Stages in the Evolution of the Avian Palate A, Dromceus. B, Gallus. C, Rhea. D, Tinamou. E, Larus. F, Portionof the palate of a Penguin to show the heniipterygoid. G, The hemipterygoid,side-view. Vo. = Vomer. Mx. = Maxillo-palatine. Pt. — Pterygoid (I, 111.A. Pc, III. C = Pterygoid). Pa. = Palatine. H. pt. = Hemipterygoid. will be found to articulate with the pterygoids by means of atrue joint—opposed bones having glenoid surfaces. Now between the type of palate, as we have remarked, PHYLOGENETIC 45 exhibited by the Struthious birds and that of the Carinate or flying birds, such as is seen in the Fowl, for instance, thereappears to be a very wide gap. A study of the palate of the nestlings of the Carinate orNeognathine group, however, will show conclusivel)- that thisgap is apparent only, and not real. In the skull of the )OungPenguin, for example, the palatine and the pterygoid articulate,not by a joint, but by overlapping suture ; the pterygoid termin-ating, moreover,

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