New Mexico Geological Society Annual Spring Meeting — Abstracts

Numerous reptile footprints are preserved as raised casts on a single bedding plane of the lower part of the Anton Chico Member of the Moenkopi Formation along Bluewater Creek, Cibola County. New Mexico at New Mexico Museum of Natural History locality 356 (SE1/4 NE1/4 NW1I/4 SE1/4 sec. 36, TI3N. R12W). This bedding plane is developed in grayish red, ripple-laminar to massive sandy siltstone 0.5 m above the contact of the Moenkopi with the underlying Permian San Andres Formation.

The reptile footprints are of two types: (1) striated ridges similar to those described from the Early Triassic Red Peak Formation of Wyoming by Boyd and Loop (J. Paleo. 58: 467-476) and interpreted by them as tetrapod swimming traces; these, however, may be underprints of a tridactyl reptilian trackmaker; and (2) large-manus Chirotherium prints that are about 11 cm long, 14 cm wide and, on one trackway, have a pace of 34 cm and a stride of 54 cm; these footprints fall within the range of variation of Chirotherium footprints from the Early-Middle Triassic Moenkopi Formation in Arizona described by Peabody (Univ. Calif. Publ. Geol. Sci. 27: 295-468). The reptile footprints from Bluewater Creek are not of types known from Upper Triassic strata in the western United States. They thus are consistent with assignment of an Early or Middle Triassic age to Moenkopi strata in New Mexico.