From July 18 to August 1, 2003, Dr. Matthew Carrano led a small reconnaissance expedition to the Late Jurassic deposits of south-central Wyoming. This area is famous for housing some of the most productive dinosaur sites in the world, most notably Como Bluff. Most of these sites come from the Brushy Basin Member of the Morrison Formation, which has produced such familiar dinosaurs as Apatosaurus, Brachiosaurus, Diplodocus, Stegosaurus, Allosaurus, Ceratosaurus, and Camptosaurus.
The Morrison Formation is a widespread and thick series of geological strata. It crops out all across the West, representing a varied series of environments with small rivers and floodplains, but in places was seasonally dry or even arid. The earliest layers of the Morrison – those below the Brushy Basin Member – are not nearly as fossiliferous. As a result, the dinosaurs from these layers are less well known.
Dr. Carrano hoped to locate sites in these early Morrison strata. Such dinosaurs would have lived millions of years before the Brushy Basin forms, but may have included their ancestors. A better sample of early Morrison dinosaurs would provide the means to examine this question, and fossils of other contemporary animals would enable him to look at evolution within Morrison environments over several million years.
Accompanying Dr. Carrano were Drs. Robin O’Keefe and Christian Sidor, both from the New York College of Osteopathic Medicine. They were interested in prospecting the Sundance Formation, which lies just below the Morrison and is therefore older. This formation was deposited by a great inland ocean that covered much of the American West during the Middle Jurassic Period. Dr. O’Keefe hoped to locate plesiosaur fossils in these rocks (of course, any dinosaur fossils would be an added bonus).
To view a slideshow and read about their field work experience,