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 molluscs (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 history of the region has reduced the resolution of the problematica's original exceptional preservation, yet the fossils retain many key features. Hence, this locality has implications for our understanding of exceptional preservation, its alteration over geological history, and the planktic communities of "The Great Ordovician Biodiversification Event" (GOBE) in the planktic realm.

A new marrellomorph arthropod from southern Ontario: a rare case of soft-tissue preservation on a Late Ordovician open marine shelf

“…Another well-known marine shelf Lagerstätte, the Walcott Rust Quarry in New York, shows soft-tissue preservation largely confined to trilobite appendages (Brett et al, 1999). Finally, a few other examples of soft-tissue preservation in deep basinal environments demonstrate potential for further discoveries, but presently sampling has yielded only a low diversity of problematica (Macgabhann and Murray, 2010; Meyer et al, 2018; Peel et al, 2019). Thus, while all these sites provide critical insights, their biotas are not easily comparable to those of Cambrian Lagerstätten from open marine shelf environments.…”

Hemichordata (Enteropneusta & Pterobranchia, incl. Graptolithina): A review of their fossil preservation as organic material

“…McKerrow et al 1977;Williams 1979Williams , 1982. Meyer et al (2018) discussed 'exceptionally pre s erved softbodied problematica' from the Martinsburg Formation of Pennsylvania and showed the strong tectonic deformation of the associated graptolites. The graptolite fusellum is preserved as organic films, but is heavily fractured (Meyer et al 2018, fig.…”