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

the Coconino trackways were those made on sloped, underwater sand or mud or subaerial, damp sand. Other criteria must be used to discriminate between these alternatives (such as evidence indicating the buoyancy of the track-makers; see Brand and Tang 1991). Some other features of the Coconino trackways favour an underwater origin. McKee (1944, 1947) explained the near-absence of downslope trackways in the Coconino by the tendency of track- makers to slide down slip faces and obliterate their own tracks. However, in Brand’s (1979) study downslope tracks were produced under all four experimental conditions and were often more clearly defined than the fossil tracks. Brand suggested that the rarity of downslope tracks in the Coconino might be better explained by the underwater behavior of animals than by a preservational bias. Perhaps the track-makers tended to swim when going with the water current and adopted bottom-walking only when moving against the current. Brand (1979) reported that all five species of living salamanders walked on the bottom more than they swam, contrary to earlier observations by Peabody (1959), who stated that salamanders rarely adopted bottom-walking. McAllister (1989) has suggested that the best criteria for the recognition of underwater trackways are those that indicate the buoyancy of the track-maker. Brand and Tang (1991) described numerous Coconino trackways that they interpreted in this manner. For example, there were trackways in which the individual prints pointed in a different direction to the trackway itself. These sideways-drifting trackways often showed clear pes impressions only, with manus impressions indistinct or absent. Similar oblique and zigzag trackways have also been reported from the De Chelly Sandstone (Lockley et al. 1995) and the Corncockle Sandstone of Scotland (McKeever 1994). Furthermore, Brand and Tang (1991) described trackways that started or ended abruptly without any evidence that slumping of sand had partially obscured the trackway. In one case a trackway was seen to angle upslope before abruptly disappearing. A similar trackway then abruptly began 0.6 m further upslope and progressed across the cross-bed surface at the same angle as the lower trackway. Brand and Tang (1991) argued that these trackways were made by animals that were partially buoyant in water and drifting with currents. In laboratory experiments, salamanders were sometimes observed to drift sideways with a current while continuing to walk. In such instances the animals left trackways that resembled the oblique trackways found in the Coconino. Partially buoyant live salamanders made long scratch marks that resembled the scratches seen in some fossil prints. Given an eolian setting, no obvious explanation for these features of the Coconino trackways presents itself. Any wind strong enough to move an animal sideways on a dune would almost certainly obliterate its tracks. Suggestions have been made that these distinctive trackways were made on eolian dunes by animals employing unusual methods of locomotion – galloping, loping, trotting or jumping or sideways walking (Lockley 1992; Loope 1992). However, in studies of modern animals that employ sideways loping the toes are only slightly displaced from the angle of the trackway, unlike the sharply oblique angles of displacement observed in many of the fossil tracks. Furthermore, morphological constraints on locomotion must be considered. It is not clear that any known Permian tetrapod possessed the skeletal structure that would have been required for such unusual sideways locomotion (Brand 1992). The best explanation seems to be that these trackways were made on underwater substrates. B. Invertebrate trackways With reference to the invertebrate trackways, Brady (1939, 1947, 1949, 1961), Alf (1968) and Sadler (1993) conducted experiments with modern scorpions and spiders and concluded that under certain conditions theymade tracks on dry or damp sand that were similar to the fossil trackways assigned to Paleohelcura and Octopodichnus . Brady (1947) also noted the resemblance of some other Coconino traces to those made by modern millipedes, blattoid beetles and isopods. The Permichnium coconinensis trackway described by Kramer et al. (1995) was attributed to a running blattoid beetle. However, experimental studies clearly reveal that one animal can produce a variety of morphologies even within a single trackway and that, conversely, different animals can produce very similar track morphologies (Brady 1939; Briggs et al. 1984; Crimes 1970; Sadler 1993). Factors affecting track morphology include temperature, moisture content and slope of the track-bearing substrate and the size, speed and foot placement of the track- making organism. Another complicating factor is that fossil tracks may have been made by extinct organisms, perhaps unknown from body fossils. It seems probable that the model organisms employed in these studies has been influenced by the presumed eolian paleoenvironment of the Coconino. Thus, studies of the invertebrate traces have employed terrestrial animals, such as spiders and scorpions. Experiments with a broader range of invertebrates, including marine and freshwater forms, would be instructive. Some authors have noted the resemblance of the Coconino invertebrate ichnofossils to those of marine invertebrates (Lundy 1973, pp. 76-78), including traces made by annelids (Lundy 1973, p. 76), hexapods (Sadler 1993; cf. Manton 1973; Macdonald 1989), sand crabs (Gilmore 1928, p. 5) and eurypterids (Sadler 1993; cf. Briggs and Rolfe 1983; Hantzschel 1975). A POSSIBLE MODEL FOR COCONINO DEPOSITION The Coconino does not quite resemble any modern depositional environments that are commonly found today when considering the thickness, areal extent and details of the sedimentology (James and Dalrymple 2010). It is likely the Coconino was deposited during the Flood by depositional processes operating at rates that we have not yet been able to model in the laboratory or with the computer. However, the Coconino does have many broad similarities to sand waves. Sand waves are very common bedforms in high- energy nearshore and shallow marine tidal environments (Garner and Whitmore 2011). They usually take the form of long parallel ridges transverse to the prevailing currents (Hulscher 1996), with crestlines ranging from straight to gently curved to sinuous. Most consist of quartz sand but they may also contain abundant biogenic material and/or gravel. Sand waves are typically 1 to 15 m high, with wavelengths between 100 and 500 m, although some are larger (e.g., the 24-m-high sand waves in the Irish Sea reported by Harvey 1966). In profile, they are most often asymmetrical (Allen 1980; Hulscher and Dohmen-Janssen 2005), with steeper faces pointing in the direction of the dominant currents, although symmetrical forms also occur. The dominant internal architecture, Whitmore and Garner ◀ The Coconino Sandstone ▶ 2018 ICC 618