Paleoparadoxia
During the construction of SLAC, a "lucky mistake" brought an ancient fossil to the surface.
Paleoparadoxia is a member of a small family of large, herbivorous marine mammals that inhabited the northern Pacific coastal region during the Miocene epoch (20 to 10 million years ago). It ranged from the waters of Japan, to Alaska to the north, and down to Baja California, Mexico. Paleoparadoxia had cousins, Desmostylus, Cornwallius, Vanderhoofius, and an ancestor called Behemotops . This entire family has been terminally extinct for the last 10 million years; they have no living descendants.
(click on the image for more views of the fossil)
The fossil skeleton on display was unearthed at SLAC in October 1964, during the excavation for the linear accelerator beam switchyard. It was found in sediments deposited about 15 million years ago. This display, a plaster cast replica of the actual fossil, was assembled by Adele Panofsky (see her report entitled Stanford Paleoparadoxia Fossil Skeletal Mounting, SLAC-Pub-7829) and engineered by John Flynn, with assistance by many SLAC staff members.
This specimen is the only complete post-cranial skeleton of Paleoparadoxia discovered in North America. It is especially fortunate that it was found in such an unusually well-preserved state. This skeleton mounting illustrates the swimming action of these animals. Notice that the front limbs were the source of Paleoparadoxia's swimming power while the rear limbs were used for steering and balance. The display illustrates the underwater habitat and other organisms that would have been present when Paleoparadoxia lived here.
Paleoparadoxia was a herbivorous marine mammal that lived in the warm, shallow waters of the coastal habitats of the northern Pacific Ocean, feeding primarily on sea weeds and sea grasses (see a depiction of Paleoparadoxia in it's native habitat). The jaws and the angle of the teeth resemble a back-hoe bucket. Its body was well adapted for swimming and underwater foraging, but not for extended deep-sea living or deep diving. Like the modern-day seal, Paleoparadoxia probably came on shore for breeding and basking in the sun. Paleoparadoxia is not a dinosaur, it is a mammal!
A number of real fossil specimens are exhibited on the sand under Paleoparadoxia. These specimens were found in the same fossiliferous sandstone formation as Paleoparadoxia.
