Nematode trails from the late triassic of Pennsylvania

Abstract

A new occurrence of nematode trails has been identified in cyclic lacustrine reddish brown siltstone deposits of the Late Triassic Fassaic Formation at Birdsboro, Pennsylvania. During lake regression, shoreline sediments covered by a thin film of water allowed free movement of the nematodes as well as production of surficial sinusoidal trails. Continued desiccation of these deposits resulted in mudcracking. Tool marks and occasional raindrop impressions point to subsequent rainstorms that carried in sediment which covered these previous traces. The assignment of the fossil sinusoidal trails to the ich‐nogenus Cochlichnus suggests that nematodes may have an ichnologic record that dates back to the Pre‐cambrian, and they are an important producer of this ichnotaxon.