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Virtual Visitor Center at SLAC

Fossil Specimens

The numbered items exhibited on the sand below the Paleoparadoxia fossil are all real fossil specimens found in the same fossiliferous sandstone formation as Paleoparadoxia. Click on the thumbnail image for a larger view of the fossil or take a tour.

Fossil Tour, #1 Shark teeth from a Mako shark, Isurus species. Isurus shark teeth are common in our SLAC sediment. The sandstone rock on which the teeth are displayed contains a small fragment of fossil bone. It is from the same sandstone formation in which the Paleoparadoxia was discovered. Several mako shark teeth were found between the ribs and other bones.
Fossil Tour, #2 Left mandible of a delphinoid cetacean, a long-snouted species of porpoise. The nearly complete left jaw was found with one tooth nearby. We can estimate that this animal possessed approximately 100 teeth.
Fossil Tour, #3 Cetacean right humerus with a fragment of the ulna found in articulation. These specimens are upper forelimb bones of a medium-sized toothed whale.
Fossil Tour, #4 Vertebrae of a delphinoid cetacean, a caudal (tail) vertebra and a partial, probably dorsal, vertebra.
Fossil Tour, #5 Crassatella clam with preserved shell material. These clams lived just below the sandy sea floor. The presence of several burrowing type clams found in SLAC sediments indicates a sheltered, sandy bay or estuary habitat present here at that time.
Fossil Tour, #6 Dosinia clams, internal molds with some shell material still adhering. These clams lived a few inches under the surface of the sand. They were a warm-water species, which tells us that Paleoparadoxia and all these other organisms required a more tropical habitat than exists here today.
Fossil Tour, #7 Clementia conradiane (Anderson). An incomplete clam specimen embedded in the surrounding rock. The specimen retains some of the concentrically-sculptured shell.
Fossil Tour, #8 Fossil snails. These are displayed on a water-worn boulder containing fossil bones and shells. It was uncovered in the excavations for PEP in 1977. These Bruclarkia barkeriana (Cooper) snails were found in a concentrated deposit which may indicate a gregarious type of organism. Certainly, they were the most common snail in that deposit.
Fossil Tour, #9 Natica sp. A few of these Moon Snails (naticid snails) were found in the same deposit as the much more common Bruclarkia snails.
Fossil Tour, #10 Trophosycon ocoyana (Conrad), small Ficus snails. These were also found with Bruclarkia, but much less commonly.
Fossil Tour, #11 This specimen contains three mammalian vertebrae in articulation. It appears exactly as it was found; no preparation work has been done on it.
Fossil Tour, #12 Saxidomus clams lived buried in the sand, sending up long siphon tubes to the surface to feed on small organisms in the sea water.
Fossil Tour, #13 Mytilus mathewsonii, variety expansus, is a fossil mussel cast. Although almost none of the original shell material is preserved, the distinctive shape of this creature is still clear.
Fossil Tour, #14 Sandstone rock from the Paleoparadoxia dig contains brown traces of plant material.
Fossil Tour, #15 Spisula clams, two sandstone casts, still retaining some of the original shell material. The two hinged shells have been preserved in their closed position, which indicates that they died while still buried in their burrows. Clams that are removed from the sand by predators or some other action, die and are found with their two valves open or separated. Note that some of the other clam specimens exhibited here are also closed.
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