Field and laboratory studies on the Coconino sandstone (permian) vertebrate footprints and their paleoecological implications

Abstract

The fossil footprints in the Coconino Sandstone have long been considered to be evidence for eolian deposition. I conducted field study of the fossil footprints in Hermit Basin, the Grand Canyon, and laboratory studies of modern amphibian and reptile footprints on dry sand, damp sand, wet sand, and underwater sand. Five species of salamanders all spent the majority of their locomotion time walking on the bottom, under water, rather than swimming. The experimental animals produced footprints under all test conditions, both up and down the 25° slopes of the laboratory “dunes”. Toe marks and other details were present in over 80% of the fossil tracks, underwater tracks, and wet sand tracks, but less than 12% of the dry sand and damp sand tracks had any toe marks. Dry sand uphill tracks were usually just depressions, with no details. Wet sand tracks were quite different from the fossil tracks in certain features. The fossil tracks were most similar to the underwater tracks. These data suggest that the Coconino Sandstone fossil tracks should not be used as evidence for eolian deposition of dry sand.