Giant Eocene bird footprints from Northwest Washington, USA


Corresponding author.


Abstract.  Tridactyl bird footprints preserved in Lower Eocene sandstone of the Chuckanut Formation in Whatcom County, Washington, USA, were made by a species of giant ground bird that walked along the subtropical lowland riverbank. The morphology and age of the tracks suggest the track maker was Diatryma (? = Gastornis). Although these birds have long been considered to be predators or scavengers, the absence of raptor-like claws supports earlier suggestions that they were herbivores. The Chuckanut tracks are herein named as Rivavipes giganteus ichnogenus and ichnospecies nov., inferred to belong to the extinct family Gastornithidae.