Thespesius occidentalis

Leidy, J., 1860, Extinct vertebrata from the Judith River and Great Lignite formations of Nebraska., Transactions of the American Philosophical Society 11, pp. 139-154 : 151-152

Thespesius occidentalis .

Several vertebrae, together with a first phalangial bone , from Nebraska, appear to indicate a deino-saurian as colossal as the Iguanodon of England, or the Hadrosaurus of New Jersey. Two of the specimens are exceedingly like mammalian lumbar vertebrae, especially those of the Elephant or Mastodon, and might readily be taken for such, were it not that they possess well marked processes for the articulation of chevron bones. One of the vertebrae from near the trunk, and another, which I suspect to belong to the same animal, from near the end of the tail, together with the phalanx, were discovered by Dr. Hayden, in the Great Lignite Formation, at Grand River, Nebraska. Another large vertebra from near the trunk, was obtained by Captain Alfred Sully, U. S. A., from an Indian, and presented to the Academy of Natural Sciences of this city. This specimen Dr. Hayden supposes to have been derived from the same locality in which he discovered the others.

The bodies of the two large vertebrae, viewed in front, ( fig. 2, plate 10 ,) are quadrately oval in outline, and notched above; the notch corresponding with the spinal canal. One of them measures about 5 inches transversely and vertically; the other, 4 1/2 inches transversely and 4 1/2vertically; and their length is about 2 3/4 inches. They are narrowed concavely from their articular borders, ( fig. 1 ,) and are bounded below ( fig. 3 ) by articular processes, for chevron bones, an inch in diameter. Their anterior articular face, ( figs. 1, 2 ,) is moderately convex; and their posterior face concave, with a depth of nearly half an inch. Robust transverse processes broken off in the specimens, projected from the conjunction of the vertebral arch and body. The spinal canal, retained entire in the smaller specimen, is circular and one inch in diameter.

The smaller caudal vertebral body, ( figs. 6, 7 ,) has its anterior surface nearly plain or slightly depressed, while its posterior surface is moderately concave. Its length is about equal to its height, which is 2 inches, while its breadth is 2 3/4 inches. The first ungual phalanx, ( figs. 4, 5 ,) resembles the corresponding bones of Iguanodon and Hadrosaurus . It is 5 inches long; 4 1/2 wide at base, by 3 1/2 thick; and 4 inches wide at the distal end, by 2 1/2 thick. Deep concavities exist each side of the distal extremity for the attachment of lateral ligaments. The proximal articular surface is a transverse reniform concavity; the distal articulation a transverse convexity slightly depressed towards its middle.

Had the bones of Thespesius been found in association with the remains of Trachodon or Deinodon , or in the same geological formation, I would have suspected that they belonged to one of the latter Explanation of Figures, Plate 10.

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Figures 1—7. Vertebrae and phalanx of Thespesius occidentalis ; one half the diameter of nature.

Figure 1. Lateral view of an anterior caudal vertebra.

Figure 2. Anterior view of same specimen as the last. one.

Figure 3. Ventral view of same specimen, exhibiting the articular processes of the chevron bones.

Figure 4. Upper view of a first phalangial bone.

Figure 5. Lateral view of the same.

Figure 6. Lateral view of a posterior caudal vertebral body.

Figure 7. Posterior view of the same specimen CHELONIA.

Figures

1—7. Thespesrus occidentalis. 8-17 Ischyrotherium antiquum.