File:The dinosaurs of North America (1896) (20769759429).jpg

Title: The dinosaurs of North America
Identifier: dinosaursofnort00mars (find matches)
Year: 1896 (1890s)
Authors: Marsh, Othniel Charles, 1831-1899
Subjects: Dinosaurs
Publisher: Washington, Govt. Print. Off.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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Text Appearing Before Image:
MARSH.) BIPLODOCUS. 179 bone iu Brontosaurus. The short dentigerous portion iu front is de- curved (PI. XXY, fig. 1), and its greatest depth is at the symphysis, as shown in fig. 28 above. The articular, angular, and surangular bones are well developed, but the coronary and splenial appear to be small. THE TEETH. The dentition of Diplodocus is the weakest seen in any of the known Dinosauria, and strongly suggests the probability that some of the more specialized members of this great group were edentulous. The teeth are entirely confined to the front of the jaws (PI. XXV, fig. 1), and those in use were inserted in such shallow sockets that they were readily detached. Specimens in the Yale museum show that entire series of upper or lower teeth could be separated from the bones supporting them without losing their relative position. In PI. XXVI, fig. 1, a number of these detached teeth are shown. 29 30
Text Appearing After Image:
Fig. 29.—Sternal plate of Brontosaurus amplus; top view. Fig. 30.—Sternal plate of Morosaurus r/randis Marsh. Both figures are one-eighth natural size, a, bottom view; 6, top view ; 6', side view; V, end view; c, face for coracoid ; d, margin nest to median line ; e, inner front margin ; p, posterior end. The teeth of Diplodocus are cylindrical in form and quite slender. The crowns are more or less compressed transversely and are covered with thin enamel, irregularly striated. The roots are long and slender and the pulp cavity is continued nearly or quite to the crown. In the type specimen of Diplodocus there are four teeth, the largest of the series, in each premaxillary; nine in each maxillary, and ten in each dentary of the lower jaws. There are no palatine teeth. The jaws contain only a single row of teeth in actual use. These are rapidly replaced, as they wear out or are lost, by a series of succes- sional teeth, more numerous than is usual in these reptiles. PL XXVI, fig. 2, represents a transverse section through the maxillary, just behind the fourth tooth. The latter is shown in place, and below it is a series

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