Early adaptation to eolian sand dunes by basal amniotes is documented in two Pennsylvanian Grand Canyon trackways
Fig 2
(A) Main trackway block adjacent to Bright Angel Trail, with tracks in concave epirelief (impressions). Scale is calibrated in decimeters. (B) Sketch of main trackway surface. Note occurrence of Trackway 2 (alignments of small black spots) above Trackway 1. (C) Jumble of rocks adjacent to Bright Angel Trail, including at least two rocks with amniote tracks. (D) Counterpart block with tracks in convex hyporelief (natural casts). Scale is calibrated in decimeters.