LATE TRIASSIC DINOSAUR LOCALITIES OF LATE REVUELTIAN (R2) AGE (NORIAN), PETRIFIED FOREST NATIONAL PARK, ARIZONA

Petrified Forest National Park (PEFO) preserves the most fossiliferous nonmarine sequence across the Carnian-Norian boundary on Earth. This rock sequence encompasses, in ascending order, the Blue Mesa (Adamanian: late Carnian), Sonsela Sandstone (Revueltian: Norian) and Painted Desert (Revueltian: Norian) Members of the Petrified Forest Formation. In 1996 we initiated the Dawn of the Dinosaurs Project at PEFO to study dinosaur evolution through the Carnian-Norian interval. At that time there were only three bona fide Triassic dinosaur localities at PEFO and all were from the Painted Desert Member. Since 1996, fifteen new dinosaur localities have been found, including three from the Carnian Blue Mesa Member representing a 500% increase since the project’s inception. Thirteen dinosaur localities at PEFO are in two narrow stratigraphic intervals - one near the top of the Blue Mesa Member (e.g., Dinosaur Wash, Dinosaur Ridge) and the other near the base of the Norian Painted Desert Member (e.g., Dinosaur Hill, Dinosaur Hollow, RAP Hill, Zuni Well Mound). We have now discovered two localities (Judy’s Luck and Ted’s Tip) that are higher in the Painted Desert Member, above the Black Forest Bed. These localities yield theropods, but lack the ornithischian Revueltosaurus callenderi that is ubiquitous in dinosaur localities low in the Painted Desert Member at PEFO and in early Revueltian (R1) faunas elsewhere. Thus, we infer that these new localities represent late Revueltian (R2)time which has previously only been recognized in New Mexico.