File:Bulletin - United States National Museum (1920) (20317763100).jpg

Title: Bulletin - United States National Museum
Identifier: bulletinunitedst1101920unitfo (find matches)
Year: 1877 (1870s)
Authors: United States National Museum; Smithsonian Institution; United States. Dept. of the Interior
Subjects: Science
Publisher: Washington : Smithsonian Institution Press, (etc. ); for sale by the Supt. of Docs. , U. S. Govt Print. Off.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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OSTEOLOGY OF CAKXIV0K0T7S DINOSAURS. 55 to represent one of the double ribs such as found bj- Lambe at the posterior end of the cuirass in Gorgosaurus. A study of these rather meager materials, therefore, shows that in Antrodemus some of the abdominal ribs of the cuirass were certainly composed of three and probably four segments on each side of the median line, so that a complete section across the abdomen would consist of either six or eight distinct ossifications, with every probability of there being a single median bone connecting the two lateral series, thus making either seven or nine in all (fig. 39). FORE LIMB AND FOOT. Plates 5-7, fig. 3. The fore limb of Antrodemus as compared with the hind limb is relatively small, but the large size of the processes and the rough nature of their surfaces imply a powerful musculature. The great size of the terminal phalanges and the general structure of the foot indicate that it was used exclusively for seizing, holding, and tearing and that it had long ago lost its functions as an organ of progression.
Text Appearing After Image:
Fig. 39.âTransverse section of abdominal basket of Antrodemus, showing a tentative determination of the seg- menation of the abdominal ribs. about j nat. size. The hand is relatively of enormous size, being slightly longer that the humerus and nearly one and one-half times as long as the forearm. In general it resembles the foot of Ornitholestes, but the bones are more robust, and there is no trace with either foot of metacarpal IV. The carpus is ossified, being made up of two transverse rows, but the precise number of elements composing it yet remains to be determined. These are three digits, which have the phalangial formula of 2, 3, and 4. Digit 1 is the heaviest of the series, and digit 3 is somewhat reduced (fig. 40). In a previous article 'â I have given a detailed description of a forelimb and foot of Antrodemus, at that time referred to Allosaurusfragilis, but m order to make the present accoimt of the osteological structure of the genus complete it is here repeated with some few omissions and emendations. The fore limb figured by Marsh in the Dinosaurs of North America,- plate 11, figure 1, as being that of Allosaurusfragilis Marsh, is a composite drawing, and is not representative of the genus Antrodemus (Allosaurus), but is largely that of Ceratosaurus. ' Proc. U. S. Nat. Mus., vol. 49. No. 2120, 1915, pp. 501-513. ' Sixteenth Ann. Rept. U. S. Geol. Survey, 1896, pt. 1.

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