WAS THERE A SOUTHEASTERN DINOSAUR PROVINCE IN THE LATE CRETACEOUS?

Dinosaur remains are sparse but widespread in Late Cretaceous eastern (Appalachian) deposits. These extend from New Jersey to the Carolinas along the Atlantic side, and Georgia to Missouri along the Gulf of Mexico embayment. Nearly all such dinosaur fossils are in pericontinental marine deposits, except in parts of the Gulf Coast where there was a substantial epicontinental sea. Since dinosaurs were terrestrial, these fossils are allochthonous and the majority are isolated, typically water-worn teeth and bones. Four holotype specimens based on associated dinosaur remains come from Appalachia: two hadrosaurids and two tyrannosauroids. Hadrosaurines and basal tyrannosaurs, together with indeterminate ornithomimosaurs, comprise the vast majority of dinosaur materials found across Appalachia, and most isolated fossils are not farther determinable to subfamily or lower taxa.

Nevertheless, enough Appalachian dinosaur material has been identified to see some evidence of North Atlantic-Southeastern provincial distinction. Among distinctions, The Upper Cretaceous southeastern assemblage (including North and South Carolina and Gulf Coast sites) includes the tyrannosauroid Appalachiosaurus, abundant dromaeosaurs (especially the velociraptorine Saurornitholestes), nodosaurs, and a newly reported neoceratopsian. The northern assemblage (New Jersey to Maryland) includes the tyrannosauroid Dryptosaurus, the only reported lambeosaurine hadrosaur, and only anecdotal reports of smaller theropods. Given the sparse dinosaur record in Appalachia, even with more than 150 years of extensive collecting, it is possible that these differences are artifacts of age, exposure and preservation. Nevertheless, one logical explanation for provinciality is that the point of entry from Laramida (western North America) to Appalachia may have been a southern land extension or archipelago across the Interior Seaway, thus favoring earlier migration into the proximal Gulf Coast.