The Proceedings of the Eighth International Conference on Creationism (2018)

vertebrate tracks as evidence of animals leaving tracks on wet or damp subaerial substrates. However, subsequent field studies and laboratory experiments, using a wider variety of conditions than those employed by McKee, indicate that the conditions under which the Coconino trackways were formed should be reconsidered. Brand (1979) reported detailed measurements of fossil trackways (n = 82) along the Hermit Trail in Grand Canyon. Fossil footprints were distributed throughout the lower half of the Coconino and were almost all oriented upslope (as also reported by Gilmore 1927b and McKee 1944). Individual prints in the fossil trackways were distinct and separate. Some showed toe marks only, some sole impressions only and some both toe and sole impressions. Crescent-shaped ridges of sand commonly occurred behind the sole impressions, but were never observed to extend backwards into previous footprints. These fossil trackways were compared with experimental trackways (n = 236) made by living amphibians and reptiles under a variety of substrate conditions (dry, moist, wet and submerged). Five salamander species ( Taricha torosa , Taricha granulosa, Notophthalmus viridescens , Ambystoma tigrinum and Cryptobranchus alleganiensis ) and three lizard species ( Sauromalus obesus , Sceloporus occidentalis and Dipsosaurus dorsalis ) were employed in the experiments. The animals were placed in experimental chambers and allowed to walk up and down a slope of sand. Most of the laboratory tracks were made on 25°slopes, with some on 15° and 20° slopes. The laboratory tracks made on dry and damp sand differed in several respects from the fossil tracks. Less than 12% of the dry sand and damp sand tracks displayed toe marks or other fine details, compared with more than 80% of the fossil tracks, underwater tracks and wet sand tracks. Furthermore, sand was often observed flowing backwards into previous prints. Damp sand prints were often surrounded by jumbled pieces of “broken crust”, but this was never observed in the fossil tracks. Furthermore, the proportions of the fossil tracks were quite different from those made in dry sand, but similar to those made underwater or in wet sand. Dry sand tracks were longer than they were wide, whereas the fossil tracks, underwater tracks and wet sand tracks were shorter than their width. Other features consistently observed in wet sand tracks (such as an upslope transition from well-defined tracks to toe marks only) were notably absent from the fossil tracks. The experimental tracks most closely resembling the fossil tracks were those made underwater. Similarities included the proportion of tracks bearing toe marks, the uniform appearance of prints along a trackway and the track proportions. Brand (1996) conducted further experiments with the western newt (Taricha torosa) to study trackways made by one species under a variety of substrate conditions. Trackways were made in mud or fine sand, on level or 25° slopes and with dry, damp, wet or submerged substrates (n = 230). Measured trackway characteristics included the number of toes (manus and pes), stride (pes), pace angulation (pes), glenoacetabular length, width of trackway and mean divergence of middle three toes (manus and pes). Trackways made in wet mud most accurately recorded the number of toes per foot and the arrangement of the toes.All other combinations yielded a reduced average number of toes per foot. Trackways made on sloped, submerged mud or sand, sloped, dry sand and sloped, damp sand rarely yielded the full number of toes per foot. The position and orientation of the toe marks were distorted in trackways made by animals walking underwater or on sloped, damp sand. It is evident that substrate conditions must be considered when drawing systematic conclusions from trackways, and that trackways made on sloped cross-beds are particularly unsuitable in this respect. In this study, the experimental trackways that most closely resembled Whitmore and Garner ◀ The Coconino Sandstone ▶ 2018 ICC 617 Table 3. Areal extent and thickness of the Coconino compared to other large cross-bedded sandstone formations and some modern ergs.