File:Bulletin - United States National Museum (1914) (20316782658).jpg

Title: Bulletin - United States National Museum
Identifier: bulletinunited891914unit (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: Biodiversity Heritage Library

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OSTEOLOGY OF THE ARMORED DINOSAURIA. 45 e3^- not require the forcible mastication of that of Iguanodon or raore especially of the late Cretaceous Trachodon, in which the powerful dental battery of 2,000 teeth reached its highest perfection." Vertebral Coltjmn. The vertebral formula in Stegosaurus, as nearly as can be determined from available material, is as follows: C, 10(«); D, 17(?); S, 3; C, 45 to 47. There are no truelumbars. Some uncertainty exists regarding the exact point of separation between the cervical and dorsal region. Although slightly disarranged, the type of S. stenops, No. 4934, shows the entire number of vertebrae in front of the sacrum (including the dorso-sacral) as being 27. Marsh in his first restoration of S. ungulatus shows 26 presacrals, 4 sacrals, and 44 caudals. In regard to the caudal series it would appear that the tail of Stegosaurus, as in other dinosaurs, is not made up of a constant num- ber of vertebrae but within limits varies with the individual. Atlas.—The atlas in Stegosaurus consists of the usual fom- pieces, the intercentrum, neuracentra, and odontoid process. It resem- bles very closely the corresponding element in Camptosaurus. The intercentrum, as shown by specimen No. 4934, is a subcresceiatic block of bone, the concave side being uppermost and with the greatest diameter transverse. The upper pos- terior part of the transversely concave surface receives the odontoid whUe the anterior part of this surface'is more deeply excavated, form- ing the lower portion of the cup for articiilation with the occipital condyle of the skull. On either side of this concave portion are the articular surfaces on which the pedicels of the neuracentra rest. Viewed from behind this element presents a nearly straight ver- tical face for articulation with the axis. On either side of the inferior surface are well- developed facets for the articulation of the single-headed cervical ribs shown in figure 16, r'.
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