Tensleep Sandstone

Trace fossils

In 1932 Edward Branson and Maurice Mehl reported the discovery of a fossil trackway in the formation. A new ichnospecies, Steganoposaurus belli, was erected for these footprints. The tracks were probably made by a web-footed animal slightly less than three feet long. This creature was originally presumed to be an amphibian, but the toe prints it left behind were pointed like a reptile's rather than round like an amphibians. The actual trackmaker may have been similar to the genus Hylonomus. The ichnogenus Tridentichnus are similar footprints preserved in the Supai Formation of Arizona.