Abstract: Coconino Sandstone (Permian) Fossil Vertebrate Footprints--Paleoecologic Implications

Leonard Brand

Fossil footprints in the Coconino Sandstone long have been considered evidence for eolian deposition. Field study of the fossil footprints in Hermit basin of the Grand Canyon and laboratory studies of modern amphibian and reptile footprints on dry sand, damp sand, saturated sand, and underwater sand were conducted. Five species of salamanders spent most of their locomotion time walking on the bottom, underwater, 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 more than 80% of the fossil, underwater, and saturated-sand tracks, but less than 12% of the dry-sand and damp-sand tracks had any toe marks. Dry-sand uphill tracks usually were just depressions, with no details. Saturated-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.

AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC