New Mexico Geological Society Annual Spring Meeting — Abstracts

A partial symphyseal tooth whorl of Campyloprion sp., comprising five teeth, is reported from the Tinajas Member of the Atrasado Formation of Socorro County, southern New Mexico. The age is constrained by both fusulinid and conodont biostratigraphy to the Missourian Stage (Upper Pennsylvanian). The holotype of Campyloprion annectans, the type species of Campyloprion, is of unknown provenance, although it has been presumed to be from the Upper Pennsylvanian of Midwestern North America. Tooth whorls of Campyloprion are more loosely coiled than those of the better-known edestoid Helicoprion; the tooth whorls of both genera are shaped like logarithmic spirals. The parameter that characterizes a logarithmic spiral, the angle between a tangent to the spiral and a radius from the center, is about 60° for Campyloprion versus about 82° for Helicoprion. The New Mexico specimen is not complete enough for this angle to be determined. Determination of the genus is therefore based on the morphology of the individual teeth, particularly the serrations, which compare closely to those of the holotype of Campyloprion ivanovi from the Upper Pennsylvanian of Russia. This is the first record of Campyloprion from New Mexico, and the most complete edestoid fossil known from New Mexico.