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.

	The front of the skull showing the four teeth of the premaxillary and the anterior teeth of both maxillaries.
	The mid-palate, showing the anterior portions of the pterygoids, and the posterior teeth of both maxillaries.
	The back of the palate, showing the tooth bearing portions of the paired pterygoid bones.
	A close up of the teeth of Prognathodon overtoni.  The teeth are described by Russell (1967) as having "smooth surfaced enamel".
	The right side of the muzzle of Prognathodon overtoni showing the suture between the premaxillary and the maxillary.
	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.
	A close up, medial view of the left quadrate and attached bones.  (Labeled)
	A view of both of the lower jaws, with the various elements labeled.
	One more look at the skull from a slightly different angle. The skull is about 28 inches (70 cm) in length along the midline.
	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.