A LATE ORDOVICIAN PLANKTIC ASSEMBLAGE WITH EXCEPTIONALLY PRESERVED SOFT-BODIED PROBLEMATICA FROM THE MARTINSBURG FORMATION, PENNSYLVANIA

Abstract:  Here we report a locality containing exceptionally preserved (soft-bodied) fossils of mid-Late Ordovician age from the geologically complex Martinsburg Formation in central Pennsylvania. The fossils, which resemble specimens from Burgess Shale-type deposits, include enigmatic specimens (problematica) and phyllocarid arthropods (with preserved appendages) which are associated with graptolites. The locality is notable for preservation of a low diversity community of soft-bodied planktic animals, likely captured and rapidly buried by a turbidity current. The problematica lack sufficient anatomical detail for confident systematic placement; however, they can be superficially compared to a number of possible metazoans including: nominally/non- shelled mollusks (including veligers), cnidarians, lophophorates, or possibly aberrant tube-dwelling priapulids or polychaetes. Overall, the problematica may belong to one (or several) extinct clades or some unknown clade of animal life. The complex geologic h...