BODY VS. TRACE FOSSILS: A PRELIMINARY REASSESSMENT OF SQUIGGLES, RODS AND CLUSTERS ON NEOPROTEROZOIC BEDDING PLANES FROM THE CAROLINA TERRANE, STANLY COUNTY, NORTH CAROLINA

Ediacaran trace fossils world-wide are being re-evaluated as alternative interpretations emerge. Due to extensive biomats and lack of bioturbators, what was originally interpreted as trace fossils may be body fossils, mat induced or inorganic structures. Published reports of Ediacaran body fossils from the Neoproterozoic Albemarle Group, Carolina Terrane include Pteridinium, ?cf. Swartpuntia, Aspidella and Sekwia. Reports of trace fossils from these strata, along with new specimens at the NCMNS, are in the process of being re-evaluated.

Rod-like fossils identified as Syringomorpha nilssoni? by Gibson (1989) and subsequently re-named Oldhamia recta by Seilacher et al. (2005) may be related to Palaeopascichnus, the body-fossils of a mat encrusting tube-like organism. Clusters of bead or pellet shaped structures identified as the trace fossil?Tomaculum by Gibson (1989) are also considered body fossils; possibly another encruster or the spat growths of small polyps. Chains of bead-like “Neonerites” are either body fossils or may be the trace fossil Treptichnus.

True trace fossils appear on bedding plane surfaces as sinuous squiggles, grooves and levees with random meanders and loops. In the Carolina Terrane, these fossils were identified as Planolites beverlyensis and Planolites montanus by Gibson (1989) or as Helminthoidichnus tenuis and ? Helminthopsis by Seilacher et al. (2005), now tentatively grouped as Helminthoidichinites-type fossils. These horizontal trace fossils preserved as both positives and negatives on the same bedding plane are evidence that the organism was an undermat miner, moving between the sediment and the mat. Combining the trace fossils evidence with true body fossils with give a better sense of the paleoecology of these Ediacaran communities.

Gibson, G.G., 1989, J.Paleo. 63,1-10. Seilacher et al., 2005, Palaeogeography Palaeoclimatology Palaeoecology 227,323-356.