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Ptychodus sp. Shark’s teeth. As you can see by the large ridges running over the surface of these rounded teeth, they were for grasping slippery shellfish and gastropods and crushing them to extract the food value. These teeth are rarer than most from the area, but enough are found to give us an idea of the relative populations. They seem to be about one for very couple of hundred "dagger toothed" sharks. These are all from the Turonian of the Late Cretaceous, or about 80MYA. These were found in the same areas as our plesiosaurs and other sharks, suggesting an abundant feeding area nearby.
Various species of shark’s teeth in the more common forms. Species here include Cretolamna, Cretodus, and Squalicorax.
We can generally find any number and species of sharks here depending on the area of the quarry we are working. We can collect a few thousand easily in an afternoon. They may not be all rooted teeth and perfect, but enough remains for them to be a fairly nice aid to the study.
Once we recover the fossils they have to be catalogued, cleaned, measured, and labeled. Then they all wind up in trays. This picture is of a group of vertebrae and the largest propodial we have found to date. A propodial is a term for the proximal (closest to the body) bone in the flipper. Until we can tell if it’s a femur or humerus, we use the term propodial.
Another picture from the lab. This is of two more propodials. The top one showing the curve of the distal end which helps to identify the species. We are assuming these are mostly Trinacromerum sp. Thanks to some ID work by Elizabeth "Betsy" Nicholls of the Royal Tyrrell Museum in Alberta, Canada.
Some of our collection with lots of shark’s teeth in the back, some nice vertebrae, a section of a rib, some parts of propodials, phalanges, and some material we are just putting back together.
One of the trays of plesiosaur teeth we have collected from the site. Plesiosaur teeth have a very distictive conical shape and striations that run vertically down the sides. They are not very abundant in our site.
Dr. Standley Lewis and Dr. Ralph Gundersen, working on fossil removal. This is the gray marl covering over the granite beds.
The tools of the trade. Rock hammer, chisel, icepick, and brushes. Plus boxes for carrying out the material we do find.
Plesiosaur neural spine deeply embedded in the marl. We had to use the chisel and very carefully remove the fractured pieces for later glueing together.
Some views of the Alzadasaurus{ Dr. Ken Carpenter's new paper now puts Alzadasaurus as a junior synonym of Styxosaurus snowii. Paludicola 1999. }from the South Dakota School of Mines and Technology Museum of Geology. I was trying to find areas of the skeleton that would help in identification of the same bones we have collected from our site. One photo I wanted some people in it for scale. This animal has one of the longest necks of any plesiosaur, about 62 cervical vertebrae. I have closeups of the pelvic and pectoral girdles as well as some of the various ribs along the vertebral column.