AN EARLY CRETACEOUS ORNITHOPOD DINOSAUR FROM CALIFORNIA

Fossils recovered from the late Aptian portion of the Budden Canyon Fo rmation of northern California represent the oldest dinosaur remains k nown from the Pacific Slope of North America. Eight well-preserved ele ments, including most of the lower left limb and pes, belong to a smal l ornithopod dinosaur that is similar to the hypsilophodontids Parksos aurus and Hypsilophodon, although they may represent a new taxon. The late Aptian age, documented by ammonites found in association with the vertebrate remains, suggests that this specimen is probably 20-30 mil lion years older than any dinosaur previously known from the western m argin of North America.