STL Science Center

STL Science Center

01 February 2013

Your Head Is On Backwards

Starting this set of months off correctly. As a background for those of you who do not know what I am doing these days, I am in graduate school, changing careers a bit, and working on getting a master's degree in biology. My project is describing and identifying a series of vertebrae which were unearthed in southern Kansas. Due to the nature of Kansas during the Cretaceous, these are most likely marine reptile vertebrae, and, to celebrate the arrival of the specimen and beginning of my work on them, the next two months will all be about marine reptiles and fish.

©Michael Skrepnick
The first skeleton of Elasmosaurus platyurus was unearthed and delivered to E.D. Cope in 1868. Cope, in his excitement, and the absolute secrecy with which he examined the skeleton, at the revelation of the skeleton, originally placed the skull on the caudal vertebrae and left the cervical vertebrae to stretch out "behind" the animal as an exceedingly lengthy tail. Contrary to popular belief Cope actually caught his mistake at about the same time as Joseph Leidy (Leidy did not discuss his revisions of the specimen with Cope) and attempted to rush a reprinting of his announcement of the skeleton and its official description. The reprinted, and filled with errors, republication was even in circulation prior to the Marsh publication on Elasmosaurus which many attribute to the popular myth of Cope being embarrassed by Marsh about Elasmosaurus. Regardless, the long thin neck of Elasmosaurus is somewhat cryptic as a neck as is; it is far more slender than one would expect for a long organism like Elasmosaurus is and could be fairly easily mistaken for a tail (Everhart 2005). The long neck, in fact, possessed 71 cervical vertebrae; nearly 4 times the amount of vertebrae belonging to the tail (there are 18 caudal vertebrae). At approximately 12m (40ft) Elasmosaurus could have weighed in at nearly 2000kg (2.2tons).

Elasmosaurus, being a long necked plesiosaur, was a carnivorous creature living in a near shore environment in the Western Interior Seaway of what is now North America. At the time the Western Interior Seaway cut what is now North America in half, creating two continents (Appalachia in the east and Laramidia in the west) and the shallow ocean was the home of a multitude of species. This large number of species, especially of smaller (and hence lower on the food chain) fish and invertebrates, led to an explosion in larger predators as well, of which Elasmosaurus was one. How is it such a successful predator? We shall examine this over the next week, starting tomorrow morning.

Everhart, M. J. (2005). Oceans of Kansas - A Natural History of the Western Interior Sea. Indiana University Press, Bloomington, Indiana, 344 pp.

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