New Mexico Geological Society Annual Spring Meeting — Abstracts

During the last five years the Mesalands Dinosaur Museum has conducted the Dawn of the Dinosaurs Project at Petrified Forest National Park, Arizona. The focus of this project is to discover new dinosaur localities and to study the paleoecological setting the diversification of early dinosaurs. Since, 1996, field crews from the Mesalands Dinosaur Museum have found fourteen new dinosaur localities to add to the previously known three.

In the Summer of 2000, two new localities were discovered which are associated with the Black Forest Bed in the Painted Desert area. The Black Forest Bed is a fluvially reworked volcaniclastic tuff. Ted s Tip and Judy s Luck are localities lithogenetically related to the Black Forest Bed. The fauna of these two localities includes gastropods, the metoposaurid amphibian Apachesaurus, two aetosaurs (Paratypothorax and ?Desmatosuchus), an undescribed armored crurotarsan, a phytosaur and one or more theropod dinosaurs. These localities are unusual among Revueltian-aged dinosaur faunas in lacking the omthischian Revueltosaurus.

The Black Forest Bed represents fluvial redeposition of an ash fall. Catastrophic sedimentation resulted in the preservation of the abundant logs of the Black Forest and also of the dinosaur localities. Thus, these new localities indicate an unusual relationship between an early dinosaur fauna and volcanic activity. Other Revueltian dinosaur localities are preserved in paleosols associated with channel fills that represent more typical fluvial deposition.