PALAEOSAUROPUS PRIMAEVUS: DUSTING OFF OLD MISSISSIPPIAN FOOTPRINTS

In 1849, Isaac Lea reported fossil tracks that he named Sauropus primaevus, from Mount Carbon, Schuylkill County, Pennsylvania, then the oldest vertebrate tracks ever reported. In 1902, O. P. Hay constructed a new ichnogenus Palaeosauropus for this ichnospecies, and Palaeosauropus is one of the most important Mississippian tracks identified in North America.

The Reading Public Museum (RPM), Pennsylvania, has the “Herbein collection” of approximately 300 fossil specimens donated to the museum in 1933. These specimens were discovered near Mount Carbon, in the Mississippian, middle member of the Mauch Chunk Formation. Nearly all footprint specimens are associated with sedimentary structures, such as current ripples, tool marks, mud drapes and rain drop impressions. Most tracks are assignable to Palaeosauropus.

The holotype of P. primaevus is the specimen described and illustrated in Lea (1855) and is housed at the Academy of Natural Sciences in Philadelphia, Pennsylvania. On the holotype, digits 1 and 5 on the pes are diffuse, with digits 2, 3, and 4 strongly impressed. The manus has three apparent digits. Lea's large specimen of P. primaevus (approximately 34 by 21 inches), that included a trackway of six (6) manus/pes pairs, described and illustrated in 1855, was not found.

Historical documents, as well as a visit to Mount Carbon, Pennsylvania, enabled the identification of Lea's original tracksite. The original locality was reported to be a few hundred feet south of the former Mount Carbon Hotel. Our forensic evidence indicates the type locality for P. primaevus is approximately 180 feet south from the southwest corner of Centre and Main Streets in Mount Carbon, Pennsylvania and has the geographical coordinates of 760 11' 15” N 400 40' 45” W. The type locality is within the middle member of the Mauch Chunk Formation. Additional tracks were found at the site.