EASTERN U.S. DINOSAUR ASSEMBLAGES IN A QUANTITATIVE PALEOBIOGEOGRAPHIC CONTEXT

Dinosaurian assemblages from the eastern United States are poorly known compared to comparable-aged faunas of the American West. Limited sediment supply and smaller depositional basins, as well as limited areas of current exposure, result in these faunas being less well characterized than their western contemporaries. Eastern North American faunas were compared to those of other regions through a quantitative phenetic paleobiogeographic analysis. From this analysis, it was found that the eastern Cretaceous sites examined clustered more closely with western North American localities rather than with (for example) European faunas. For example, the Arundel Clay (Aptian, Maryland) was found to lie within a cluster containing the Aptian-Albian Cloverly Formation of Montana and Wyoming, the Paluxy Formation of Texas, and the Ruby Ranch Member of the Cedar Mountain of Utah. The Late Cretaceous Navesink, Mount Laurel, and Black Creek Formations (New Jersey, New Jersey, and North Carolina, respectively) clustered with lower diversity assemblages of western North American Campano-Maastrichtian localities, rather than the more typical high diversity sites. This may reflect taphonomic rather than paleobiogeographic controls.