ISAAC LEA'S ORIGINAL SPECIMENS OF PALAEOSAUROPUS (SAUROPUS) PRIMAEVUS

In 1849, Isaac Lea discovered fossil footprints in Mount Carbon, Pennsylvania that he named Sauropus primaevus. Hay (1902) constructed a new ichnogenus Palaeosauropus for this ichnospecies.

Our earlier research reports locate Lea's original discovery site for Palaeosauropus (Sauropus) primaevus in red sandstones and shales of the Mississippian Mauch Chunk Formation on the west side of Centre Street in Mount Carbon, PA. The holotype of P. primaevus is the specimen described and illustrated in Lea 1853 and is housed at the Academy of Science in Philadelphia (ANS9752). The holotype measures approximately 18 x 30 cm. and contains a manus/pes pair.

Lea (1853, 1855) describes and illustrates a red sandstone slab, measuring about 86 x 53 cm with a trackway of six manus/pes pairs. The authors have located a plaster cast specimen at the Smithsonian Museum (USNM487148), accredited to Isaac Lea bearing the inscription “Sauropus primaevus Lea New Red Sandstone Pottsville Pa”, measuring approximately 64 x 46 cm with a trackway of 3 pair of manus/pes. There has been some damage to the plaster specimen, so that only some digit impressions of two additional manus/pes pairs can be seen.

Molds of the Smithsonian's and Academy's specimens, in reverse image, compare very favorably to Lea's 1855 illustration of his trackway specimen, as well as to the taxonomic description of P. primaevus. Lea's 1855 illustration is a mirror image of a mold of the original trackway specimen. The holotype is a piece of Lea 1885 trackway specimen and is the topmost manus/pes pair. The Smithsonian cast is the remaining portion of the original trackway specimen (minus the holotype piece). Additional track specimens collected near Pottsville, PA are attributable to the P. primaevus holotype. Additional study is needed in order to describe fully the taxonomy of these recently collected specimens.