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Leidy, J.,


[Descriptions of a number of fossil reptilian and mammalian remains]. 

Proc. Acad. Nat. Sci. Phila. 5:325-327.

Copyright © 2002-2012 by Mike Everhart

ePage created 10/31/2002; updated 11/16/2012



LEFT: Thirteen vertebrae described by J. Leidy (1851) as the type specimen of Cimoliasaurus magnus (ANSP 9235). In the collection of the Academy of Natural Sciences of Philadelphia. Close up of single vertebra (2nd from right, bottom row) here .... all show signs of pyrite disease.

Wherein Joseph Leidy describes and names the first two species of plesiosaurs found in the United States; Cimoliasaurus magnus from New Jersey and Discosaurus vetustus from Alabama. In 1865 Leidy re-described these specimens and provided figures. (See Leidy, 1865)

 1851.]                                                                                                         325

   (previous non-Leidy text on this page omitted)

   Dr. Leidy exhibited a number of fossil reptilian and mammalian remains which he characterized verbally as follows :

   Cimoliasaurus magnus Leidy. A saurian established upon thirteen vertebræ, apparently from one individual, found in the Green Sand of New Jersey, and preserved in the Museum of the Academy. Two of the vertebræ are posterior dorsal, the remainder lumbar. All of them have the processes broken off, excepting one of the dorsal, which still preserves its transverse processes nearly entire.

   The vertebral bodies are broader than they are long, being compressed cylindroidal in form, gradually expanding from their middle to the angular edge of the articular surface. The latter are slightly concave, about one-half the depth of those of Poecilopleuron Bucklandii, Delsch., with the centre a little prominent, and becoming slightly convex towards the edges.

   The transverse processes remaining in one of the specimens of dorsal vertebræ are prominent, thick, irregularly cylindroid tubercles, projecting from the middle of the side of the vertebral body, with an oblique articular facet for the rib. In the lumbar vertebræ the transverse processes incline downwards from the lower part of the bodies laterally, as in Mososaurus [sic].

326                                                                                                  [December,

                                          Measurements of the largest dorsal vertebræ.

Length of body,                                                                      2 3/4 inches

Breadth of body at articular faces                                        4 1/2 inches

Heighth of body at articular faces                                        3 1/2 inches

Depth of articular faces,                                                       2 lines [1/6 in]

Length of transverse processes,                                          1 inch

Diameter of transverse processes,                                      1 1/2 inch

Breadth of spinal canal,                                                        1 inch

                                            Measurements of the smallest lumbar vertebra.

Length of body                                                                      2 inches.

Breadth of body                                                                    2 3/4 inches

Heighth of body                                                                    2 in. 10 lines

Depth of articular surfaces,                                                 2 1/2 lines

Discosaurus vetustus Leidy. A saurian founded upon a single vertebra with the processes broken away, obtained by Mr. Joseph Jones from the cretaceous formation of Alabama.

   The body is about as large, and has a general resemblance to that of Plesiosaurus pachyomus, Owen, represented in fig. 3, tab. xx, of the Monograph on the fossil reptiles of the Cretaceous Formation. It differs most remarkably from the vertebral bodies of Plesiosaurus, in the articular faces forming distinct concave disks, separated from the body by a constriction or short neck. The body is relatively much broader in relation to its length than in Plesiosaurus. The specimen is a cervical vertebra. Upon each side it has a deep, concave, transversely oval, costal pit, with a very prominent, sharp border.


Length of body,                                                                      2 inches.

Breadth of body,                                                                    2 3/4 inches.

Heighth of body

Depth of articular surfaces,                                                  2 1/2 lines.

Transverse diameter of costal pit,                                       1 1/4 inches.

Vertical diameter of costal pit,                                             11 lines.

Depth of costal pit,                                                                4 lines

   The fragment of a vertebra described by Dr. Dekay in the Annals Lyceum of Nat. Hist. of New York, Vol. 3, p. 165 and represented in pl. 3, fig. 11, from the Green Sand of New, Jersey, and observed by that gentleman to be allied to the Plesiosaurus, probably belongs to the Discosaurus vetustus.

   The vertebra described by Dr. Harlan in the Journal of this Academy, Vol. 4, p. 232, and represented in pl. xiv, fig. 1, was referred to the Plesiosaurus. The specimen was from the Green Sand of New Jersey, and is preserved in the cabinet of the Academy. It does not belong to a saurian, but is a posterior dorsal vertebra of a cetacean allied to the Delphinus. The vertebral body is relatively twice the length of what it is found to be in the latter. The transverse process is also relatively short and broad; at its extremity it has an articular facet for the head of a rib.

   The vertebra is probably the type of a form existing in a distinct genus of ancient Cetacea, for which I propose the name Priscodelphinus. The species I

 1851.]                                                                                                           327

dedicate to the memory of Harlan, under the name Priscodelphinus Harlani Leidy.

   In the collection of the Academy there are preserved two caudal vertebra of a young cetacean, from the Green Sand of Jersey. These specimens are larger than the dorsal vertebra just described, but, from the length of their bodies, and the width antero-posteriorly of the neural arch, I suspect them to belong to the same genus of the latter, but a larger species, for which I propose the name Priscodelphinus grandævus Leidy.

                          Measurements of the posterior dorsal vertebra of P. Harlani.

Length of body,                                                                               2 inches.

Breadth of articular surfaces,                                                         8 lines.

Length of transverse process,                                                        1 1/2 inches.

                             Measurements of two caudal vertebræ of P. grandævus.

Length of body,                                                                               2 3/4 inches.

Breadth of epiphysial surfaces,                                                     2 1/4 inches

The two species of Priscodelphinus possess more than ordinary interest, from their being the first mammalia which have been discovered in the cretaceous formations.

   (... remainder of Leidy note omitted)

Other Joseph Leidy ePapers:

Leidy, J. 1851. [Descriptions of a number of fossil reptilian and mammalian remains].  Proc. Acad. Nat. Sci. Phila. 5:325-327.

Leidy, J. 1854. [Remarks on exhibiting to the Society four vertebræ of a huge extinct Saurian from Arkansas]. Proc. Acad. Nat. Sci. Phil., 7(3):72, pl. II. (for meeting of May 23, 1954)

Leidy, J. 1859. [Xystracanthus, Cladodus and Petalodus from the Carboniferous of Kansas]. Proc. Acad. Nat. Sci. Phila., 11:3.

Leidy, J. 1865. Memoir on the extinct reptiles of the Cretaceous formations of the United States. Smithsonian Contrib. Knowl. XIV (6) 1-135, pls. I-XX. (Section on Cimoliasaurus magnus and Discosaurus vetustus)

Leidy, J. 1868. [Photographs of fossil bones]. Proc. Acad. Nat. Sci. Phila. 20:316. (Meeting of December 22, 1868) - Leidy shows photographs of the bones of mosasaur reported to be 70' in length.

Leidy, J. 1870. (Remarks on Elasmosaurus platyurus). Proc. Acad. Nat. Sci. Phil. 22:9-10. (for meeting of March 8, 1870) (Picture)  Leidy criticizes Cope's reconstruction of Elasmosaurus and states that Cope had put the head on the wrong end.

Leidy, J. 1870. [Remarks on ichthyodorulites and on certain fossil Mammalia.]. Proc. Acad. Nat. Sci. Phil. 22:12-13. (The description and naming of Xiphactinus audax)

Leidy, J. 1870. On the Elasmosaurus platyurus of Cope. Amer. Jour. Sci. ser. 2, 49(147):392. (for May meeting) (Leidy criticizes Cope's reconstruction)

Leidy, J. 1870. On Discosaurus and its allies. Amer. Jour. Sci., ser. 2, 50(148):139-140.