DOGGY GO WALKIES?: FIRST DISCOVERY OF FOSSIL VERTEBRATE TRACKS AT VASQUEZ ROCKS IN THE VASQUEZ FORMATION (EOCENE-OLIGOCENE) IN AGUA DULCE, CALIFORNIA

Vasquez Rocks County Park in Agua Dulce, Los Angeles County, California is a famous filming location due to the “alien” appearance of the angled rock outcrops, appearing in Star Trek and other shows and films. It is also frequently visited by hikers and others who enjoy traversing the beautiful terrain. On a recent geology class trip to the park, we discovered fossil tracks in situ on the surface of a mudstone layer. The layers above and below the footprint lamination vary in composition from mudstone to sandstone to conglomerate, showing evidence of both rapid deposition (e.g., mudflows and floods) and periods of exposure (e.g., mudcracks). Additionally, there is evidence of soft sediment deformation in the form of a large clastic dike, convoluted beds, and flame structures.

There are at least three tracks preserved of similar size (5.5 cm long), but only one is distinguishable in any detail. This track clearly shows four toe impressions and a metacarpal pad, indicating that the trackmaker was a digitigrade carnivoran mammal. From comparison with tracks in the literature, we have determined that the track was made by a canid. Given the small size and its presence in the Eocene-Oligocene Vasquez Formation of North America, it is likely that the trackmaker was a hesperocyontine. This marks the first discovery of a fossil vertebrate track in Vasquez Rocks County Park.