AN INVESTIGATION OF THE PALEOSAUROPUS PRIMAEVUS TYPE LOCALITY: AN ICHNOFOSSIL ASSEMBLAGE FROM THE MISSISSIPPIAN MAUCH CHUNK FORMATION, SCHUYLKILL COUNTY, PENNSYLVANIA

Ichnofossils from the middle member of the Mississippian Mauch Chunk Formation are unusual, if not rare, yet they are important because each new specimen increases our understanding of Mississippian terrestrial biodiversity. The site we investigated is at Mount Carbon, PA, and is where in 1849 Isaac Lea discovered Paleosauropus (Sauropus) primaevus, one of the first vertebrate footprints discovered in North America that still represents one of the oldest well known examples of tetrapod footprints.

In Mount Carbon, PA, the 490-meter-long outcrop of middle Mauch Chunk sandstones and shales on the west side of Centre Street, south of Main St., was closely examined, measured, and partially excavated. The Mauch Chunk Formation at this locality is characterized by fining upward fluvial and overbank deposits; the shallower portions of the channels fills are characterized by mud-draped, ripple-laminated sandstones providing a unique taphonomic window into a Mississippian tetrapod and invertebrate assemblage.

During section measuring, paleobotanical remains, new invertebrate traces, and two examples of tetrapod footprints were recovered. A partial excavation of the talus (float) at the foot of the place in the outcrop where Lea discovered P. primaevus has provided several examples of invertebrate traces (including Diplichnites), and more than three dozen examples of tetrapod footprints, including nearly complete manus and/or pes imprints, and numerous two or three digit impressions. These tetrapod footprints are best interpreted as extramorphological variants of Paleosauropus (Sauropus) primaevus.