New Mexico Geological Society Annual Spring Meeting — Abstracts

New Mexico has an important record of Late Pennsylvanian coprolites from the central portion of the state (Kinney Brick quarry, NMMNH locality 345; Tinajas locality, NMMNH locality 8042). A third, new, significant locality for vertebrate coprolites, NMMNH locality 3276, occurs in a road cut of NM Highway 82 that exposes strata of the Missourian Beeman Formation in the Sacramento Mountains in the southeastern portion of the state. The majority of coprolites from this locality are large in size (up to 5 cm long) and spiral in form. The coprolites are three-dimensional, relatively undeformed and readily separable from the matrix. In contrast, the Kinney coprolites are compressed and occur in finely-laminated shale, whereas the Tinajas specimens represent an intermediate condition, with more three-dimensionality, although they also occur in laminated shale.

Approximately five morphotypes are represented in the Beeman coprofauna. Type one coprolites are macrospiral heteropolar in form and resemble Liassocopros, but they differ from the Mesozoic genus in being narrower and proportionally more elongate. Type two coprolites are heteropolar in morphology. They resemble the Permian ichnotaxon Hyronocopros, but some examples are more spindle-shaped with more acute tips than is typical of Hyronocopros. Type three coprolites are macrospiral heteropolar and appear to represent Heteropolacopros. Type four coprolites are conical in shape with spiral structure visible in cross section. Type five coprolites are poorly preserved but represent another spiral form. There are a few poorly-preserved coprolites that could be non-spiral.

The Beeman coprofauna is important in providing an important transition between the coprofaunas of the earlier Upper Paleozoic, which mainly consist of compressed specimens from laminated shales, and the abundant three-dimensional coprofaunas of the Early Permian. The ichnofauna is distinctive in that virtually all the coprolites are spiral in form. Although no fish fauna is known from the Beeman Formation, the majority of the Beeman coprolites are spiral, so they likely represent chondrichthyans with helical anal valves.