A MID-MIOCENE CANID TRACKWAY FROM THE THUMB MEMBER, HORSE SPRING FORMATION OF THE LAKE MEAD REGION OF SOUTHERN NEVADA

Trace fossils, including fossil tracks, provide snapshots of the movements and behaviors of extinct organisms. Trace fossils are also valuable in that they provide evidence of presence in the absence of body fossils.

The Horse Spring Formation (HSF) in the northern Lake Mead Region contains a record of mid-Miocene basin-fill sedimentation that occurred during the most active period of crustal extension that influenced this region at the time. While, to date, no body fossils have been recovered from the HSF, numerous tracks of mammal and bird origin have been reported.

We are reporting preliminary results of a trackway slab recently recovered under a Bureau of Land Management permit from the Echo Hills area just north of Lake Mead. The prominent feature of this slab is a canid trackway, tentatively attributed to the ichnogenus Canipeda, consisting of about nine tracks in an apparent rotary gallop gait. The slab also contains numerous tracks that were produced by at least two different bird types. We are investigating these tracks using a combination of 2D and 3D photography techniques including photogrammetry to examine these tracks in further detail. We hope that a closer examination of the canid trackway will allow us to determine the gait, travel speed, and potentially the identity of the track maker. Initial impressions are the canid tracks were produced by either a borophagine canid or a species of the canine genus Leptocyon.