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Williston, S. W. and R. L. Moodie. 1913.

New plesiosaurian genus from the Cretaceous of Nebraska.

[Ogmodirus martini]

Bulletin of the Geological Society of America  24: 120-121.



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ePage created 04/06/2005; updated 03/09/2010

Wherein Williston and Moodie, in the abstract of a paper presented at the 1912 meeting of the Paleontological Society in New Haven, Connecticut, name a new genus and species of plesiosaur from Cloud County, Kansas. Note the original spelling of Ogmodirus martini. When Moodie (1916) referred to the specimen, he added an extra "i" added to "martinii."  A year later, Williston and Moodie (1917) published the paper describing this species and also included the mis-spelling. Although the mis-spelling has been used in the literature since then, the original genus name (martini)is the correct spelling (see also Schultze, et. al., 1985, p 50; Storrs, 1999). Note that when it was described in more detail (Williston and Moodie, 1917) mention was made of bite marks from sharks one one of the propodials. The bite marks have seen been identified as those of Squalicorax from the serrations that are preserved.







     The new genus is a member of the widely distributed family, the Elasmosauridae, and is based on a complete series of cervical vertebrę with limbs and girdle elements. The distinguishing characters of the new genus are the short, uniform centra of the cervical vertebrę from Cloud County, Kansas. The characters of the limbs show the animal to have been a young but nearly mature individual. There are no evidences for the formation of the articular surfaces of the ends of the propodials for articulation with the mesopodial elements. The cervical centra have on the ventral surface throughout a pair of vascular foramina, and the surfaces of all the skeletal elements show evidence of the presence of a richly vascular periosteum. There are 51 cervical vertebrę preserved with a total length of nearly two meters. The individual vertebrę increase in length and breadth according to the following measurements:

     3d cervical vertebrę     20 mm. long        30 mm. wide
     6th     "             "            23   "       "          32    "     "
   12th     "             "            30   "       "          38    "     "
   20th     "             "            34   "      "          44    "     "
   30th     "            "           
41   "       "          52    "     "
"            "            45   "       "          67    "     "
   45th    "             "            45   "       "          67    "     "
"            "            46   "        "         72    "     "

                   REGISTER OF THE NEW HAVEN MEETING           121

The new generic and specific terms Ogmodirus martini are proposed for the new animal.
     The limbs are short and heavy, with the ends of the propodials not modified for the reception of the mesopodial elements. The anterior and posterior propodials both exhibit traces of the peculiar vascular canals and cavities so often described for the plesiosaurs. In the opinion of the junior author this condition is a persistence of an embryonic condition confined to the plesiosaurs and indicating a distinct evolution in that group. The developing long bones of all vertebrates show precisely the same condition as is exhibited by the adult propodials. The fact that they seem to be more exaggerated in some embryonic plesiosaurian propodials would go to show that the character has been deeply impressed on the organization of some of the group. Other members of the Plesiosauria show this character very little, or not at all. Until the plesiosaurs are better known, no
definite solution of the problem can be attained; but it is suggested that the more generalized and plastic forms of the group will be found to exhibit this character, while the development of this character has been obliterated in other forms.








Suggested reading:

Moodie, R. L. 1916. The structure and growth of the plesiosaurian propodial. Journal of Morphology 27: 401-410.

Schultze, H.-P., L. Hunt, J. Chorn and A. M. Neuner. 1985. Type and figured specimens of fossil vertebrates in the collection of the University of Kansas Museum of Natural History, Part II. Fossil Amphibians and Reptiles. Miscellaneous Publications of the University of Kansas Museum of Natural History 77: 66 pp.

Storrs, G. W. 1999. An examination of Plesiosauria (Diapsida: Sauropterygia) from the Niobrara Chalk (upper Cretaceous) of central North America, The University of Kansas Paleontological Contributions, (N. S.), No. 11, 15 pp.

Williston, S. W. and R. L. Moodie. 1913. New plesiosaurian genus from the Cretaceous of Nebraska. Bulletin of the Geological Society of America 24: 120-121. (Abstract reporting Ogmodirus martini - note original spelling)

Williston, S. W. and R. L. Moodie. 1917. Ogmodirus martinii, a new plesiosaur from the Cretaceous of Kansas. Kansas University Science Bulletin 10: 61-73, figs. 1-3., plates 1-5. (see also Moodie, 1916)