| Potomac Group | |
|---|---|
| Stratigraphic range: Cretaceous, | |
 | |
| Type | Group |
| Sub-units | Patuxent Formation, Arundel Formation, Patapsco Formation, Raritan Formation |
| Underlies | Raritan Formation, Magothy Formation |
| Overlies | Boonton Formation |
| Location | |
| Region |  Delaware,  Maryland,  New Jersey,  Virginia |
| Country |  United States |
The Potomac Group is a geologic group in Delaware, Maryland, New Jersey, and Virginia. It preserves fossils dating back to the Cretaceous period. An indeterminate tyrannosauroid and Priconodon crassus , a nodosaurid, are known from indeterminate sediments belonging to the Potomac Group. [1] The Potomac Group was initially believed to have been Late Jurassic in age by Othniel Charles Marsh [2] but later studies, such as Clark (1897), have found that the Potomac Group is in fact Early-Late Cretaceous (Aptian-Turonian) in age. [3] The most famous member of the group is the Arundel Formation, which preserves a high diversity of terrestrial vertebrate fauna and provides the most comprehensive look at the dinosaurian fauna of eastern North America during the Early Cretaceous. [4]
