DIVERSE ARRAY OF SOFT-SEDIMENT FOSSIL VERTEBRATE TRACKS FROM THE LAKES OF WORLD’S LARGEST GYPSUM DUNE FIELD
Prints are preserved in soft gypsum and carbonate sediment, making them extremely fragile and susceptible to rapid weathering once exposed. Some prints and trackways have an ephemeral expression, only visible when sediment moisture is high enough to create a contrast with surrounding sediment. The prints can be raised above or depressed below the surface. We interpret the raised tracks to represent the compressed sediment below the track exposed by wind erosion, and in some cases affected by diagenetic alteration to, or precipitation of dolomite.Sediment surrounding these tracks are distorted as seen in natural vertical exposures or excavations into track-bearing strata. Sediment that infills the tracks includes fine or coarse grained gypsum sand, siliciclastic mud, and dolomite. Many tracks are very fragile, but those comprised of dolomite are comparatively resistant. In addition to the prints, layers of vegetation have been found preserved beneath and above many of the tracks, and hair and possible coprolites have also been found in association with the trackways. This ongoing survey continues to discover new trackways as they are exposed from eroding sediment. This study is part of an ongoing effort to catalog and correlate sediments and trackways at White Sands National Monument to better plan for their preservation and interpretation.