The purpose of this paper is to document an Allosaurus feeding site in the Upper Jurassic Morrison Formation near Thermopolis, Wyoming, United States, and to illustrate the usefulness of Geographic Information Systems (GIS) for taphonomic reconstructions.


Geospatial data collected with a Nikon Total Station from a dinosaur quarry in the upper part of the Morrison Formation in north-central Wyoming were plotted on ArcGIS ArcScene software. The resulting three-dimensional maps indicate two distinct sauropod bone assemblages with closely associated shed theropod teeth separated by a weakly developed paleosol. Consequently, previous hypotheses that all bone elements and theropod teeth in the quarry were chronologically connected are amended. Synthesis of geological and paleontological data provides evidence that a juvenile Camarasaurus was the center of feeding activity in a shallow-water, palustrine-lacustrine setting in the lower assemblage. The high ratio of juvenile to adult allosaurid teeth suggests one or two adults in the company of several juveniles during a scavenging event. A high incidence of theropod teeth in the upper assemblage suggests that another feeding event may have occurred, but data loss from initial traditional excavation techniques precludes a more detailed interpretation. Although the Upper Jurassic Morrison Formation in the western United States yields abundant sauropod and theropod remains, few sites documenting theropod-prey interactions have been reported. Evidence of theropod feeding activities has been difficult to establish in seemingly homogeneous continental deposits with traditional excavation techniques alone. Geographic Information Systems (GIS) is a valuable tool that allows paleontologists to establish chronostratigraphic constraints in complex continental assemblages, assess the degree of time averaging, and evaluate important geospatial patterns.