File:The dinosaurs of North America (1896) (20963934141).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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170 DINOSAURS OF NORTH AMERICA. articulation. This is shown in fig. 3. In the vertebra ngured, at the base of the neural spine, there is a strong anterior projection, which was inserted into the cavity between and above the posterior zyga- pophyses of the vertebra in front. There appear to be no true lumbar vertebrae, as those near the sacrum supported free ribs of moderate size. The vertebrae in this region have both faces of the centrum nearly flat or biconcave. An anterior dorsal rib is shown below. THE SACRUM. The sacrum in the present species consists of five well-coossified ver- tebrae, and in the type specimen the centrum of the last lumbar is firmly united with it, as shown in PL XXIII. The striking feature
Text Appearing After Image:
Fig. 9.—Proximal end of rib of Brontoiaurui ezcelsns Marsh; front view. Fig. 10.—The same bone; back view. Fig. 11.—The same; superior view. All the figures are one-eighth natural size. c. cavity ; h, head; (. tubercle. about this sacrum is the large general cavity it contained. This was divided in part by a median longitudinal partition, as shown in PL XXIII, fig. 2. The septum, however, was not continuous the whole length of the sacrum, so that the two lateral cavities were vir- tually one. This extended even into the lateral processes. The trans- verse partitions formed by the ends of the respective centra were also perforate, so that the sacrum proper was essentially a hollow cylinder. The cavernous character of the sacrum is one of the peculiar features of the suborder Sauropoda, and was described by the writer when the first species of this group was discovered in this country. The

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