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Extinct fauna
A preliminary faunal study supports an older Lower Morrison by the presence of a new and more primitive species of Allosaurus (A. “jimmadsoni”). The species is characterized in comparison to the well-known Allosaurus fragilis, by the horizontal lower jugal border, manus claws less hooked and the general slenderness of the skeleton. Other evidence supporting this view lies in the primitive details of the Apatosaurus (Einstein) brain case found in direct association with a near complete skeleton. In this specimen, the occipital condyle appears proportionally smaller in comparison with the Apatosaurus preserving these morphological features from upper Morrison sites. Dr. Robert T. Bakker believes that the Apatosaurus skeleton originally from the Dana Quarry may actually belong to Eobrontosaurus. Both of these dinosaur species are reported only from lower Morrison Formation sites.
In this relatively small quarry no larger than 7000 square feet, over 15 individual dinosaur skeletons have so far been discovered, representing a variety of species, including predator and prey, both large and small. These virtually complete and exquisitely preserved skeletons tell a fascinating story which paleontologists have yet to fully explore. Current speculation suggests that the Dana Quarry site may have previously been a natural trap where herbivorous species, perished together in a shrinking water hole, possibly during a drought. The weak and dying may have gotten caught in the mud long enough to attract the attention of predators, which in turn were trapped while feeding on “easy pickings”. The feeding intensity is well supported by the hundreds of tooth sheds recovered since the discovery of the Dana site. The identified teeth belong primarily to Allosaurus and secondarily to Torvosaurus, while sheds belonging to Ornitholestes, Elaphrosaurus and Ceratosaurus are not rare. Additional support exists with the tooth marks preserved on the bones associated with the skeletons. The carnage preserved here is reminiscent of the conditions that existed in the Tar pits of Rancho La Brea, where Ice age mammals were drawn to their death by a rare predator & prey chain reaction event, which preserves an abundance of carnivore species.
So far, the Ten Sleep time capsule has produced an impressive species list: Apatosaurus, Diplodocus, Amphicoelias, Camarasaurus, Allosaurus, Ornitholestes, Coelurus, Elaphrosaurus, Torvosaurus, Ceratosaurus, Othnielosaurus, Camptosaurus, and Stegosaurus. Except for one turtle, Dinochelys, the fauna lacks species associated with an aquatic environment such as fish, amphibians, and crocodilians. The depositional environment may have been more in the way of rivers and streams with floods occurring periodically as indicated by the water worn bone fragments preserved throughout most of the producing sandy layers.
The Dana Quarry is therefore a unique site, offering an opportunity to study the associated fauna and flora together with complete dinosaur osteology from a locality representing a little known temporal stage within the Jurassic. The Dana Quarry is an unpublished locality offering unlimited fresh paleontological prospects in taphonomy and paleoecology investigations. It also has the potential as being one of the best Jurassic dinosaur sites in the North America. The Dana Quarry site has proven to be exceptionally productive, and with crews continuing to work the area, the next important discovery could be hiding under the next rock.
