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Prognathodon overtoni

A Pierre Shale Mosasaur from South Dakota in the Museum of Geology,

South Dakota School of Mines and Technology

Copyright 2000-2008 by Mike Everhart

Webpage created 07/29/00: updated 03/14/2008

Prognathodon overtoni is an example of mosasaurs beginning to diversify and specialize toward the end of the Cretaceous.  The skull is more heavily constructed, enabling the animal to exert a more forceful bite.  Prognathodon may have been closely related to Globidens, a mosasaur with ball shaped teeth that were used in feeding on clams and other shellfish. The exhibit specimen (#3393) was found in the Virgin Creek Member of the Pierre Shale formation, in Shannon County, South Dakota.  It was collected by T. R. Overton and is figured in Dale Russell's Systematics and Morphology of American Mosasaurs.  The specimen is displayed upside down, providing a look at the generally unseen underside of the skull. The following pictures show the skull and jaws of this beautiful specimen.

3393sd1a.jpg (4371 bytes) The front of the skull showing the four teeth of the premaxillary and the anterior teeth of both maxillaries.
3393sd2a.jpg (4072 bytes) The mid-palate, showing the anterior portions of the pterygoids, and the posterior teeth of both maxillaries.
3393sd3a.jpg (3365 bytes) The back of the palate, showing the tooth bearing portions of the paired pterygoid bones.
3393sd4a.jpg (3736 bytes) A close up of the teeth of Prognathodon overtoni.  The teeth are described by Russell (1967) as having "smooth surfaced enamel".
3393sd5a.jpg (3133 bytes) The right side of the muzzle of Prognathodon overtoni showing the suture between the premaxillary and the maxillary.
3393sd6a.jpg (4448 bytes) The right rear portion of the skull, showing the linkages between the various bones of the skull and the quadrates that provide the hinge points for the lower jaw.  Bones are labeled.
3393sd7a.jpg (2797 bytes) A close up, medial view of the left quadrate and attached bones.  (Labeled)
3393sd8a.jpg (6607 bytes) A view of both of the lower jaws, with the various elements labeled.
3393sd9a.jpg (5370 bytes) One more look at the skull from a slightly different angle. The skull is about 28 inches (70 cm) in length along the midline.
cooncr4a.jpg (5150 bytes) A field jacket containing the remains of a Prognathodon sp. mosasaur from the Coon Creek Member of the Ripley Formation (late Cretaceous) in western Tennessee.  More pictures of this specimen are found on the "Mosasaurus and other mosasaurs" virtual mosasaur museum page.

For more about mosasaurs, visit the Virtual Mosasaur Museum

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