25 Paleontology, Paleoecology, and Taphonomy (Posters)

Friday, 1 April 2016
8:00 AM - 5:30 PM
Exhibit Hall

TROPHIC ECOLOGY AND BIOEROSION OF MOLLUSCAN FAUNAS FROM THE LOWER WACCAMAW FORMATION AT PRINCE'S QUARRY IN SOUTHEASTERN NORTH CAROLINA

Paper number: 25-13
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Fossil mollusks from the lower Waccamaw Formation at Prince’s Quarry were investigated as part of a broader research objective to characterize regional extinction pulses in marine faunas during the Plio-Pleistocene. Students in a paleontology class from Georgia State University processed >1650 specimens by sieving, picking, and sorting bivalves with visible umbos and gastropods with intact apices. Taxa >5mm were identified to genus level and divided into “whole” (if ~85% of the shell remained) and fragmented specimens. All “whole” shells were placed in 5mm size bins, categorized by life modes using the Neogene Marine Biota of Tropical America online database, and select genera were additionally studied for signs of bioerosion.

Feeding habits, mobility, substrate relationship, and shell attachment were analyzed for bivalves at the level of genera and individuals. Gastropods were examined only by feeding habits for both genera and individuals. Bivalves were dominated overwhelmingly by suspension feeders (76% genera, 94% individuals), mostly consisting of unattached, actively mobile infauna (67% genera, 55% individuals) followed by immobile, cemented epifauna (20% genera, 37% individuals). The most abundant life modes among gastropods included predatory carnivores (53% genera, 51% individuals), browsing carnivores, and suspension feeders.

Six genera were analyzed for evidence of bioerosion including encrustation (but predatory gastropod drillholes were excluded). Bioerosion was not prevalent in Anadara (<1%) and Lirophora (~4%), moderate levels were reported for Arcinella (~14%) and Glycymeris (~15%), and high frequencies were observed for Chama (~35%) and Plicatula (~41%). Both size and life modes were considered as influencing factors in the degree of bioerosion observed. Small specimens and infauna were less likely to be bioeroded. Ongoing work will compare the results observed here for life modes and bioerosion to that of other localities nearby previously analyzed in southeastern North Carolina.

Geological Society of America Abstracts with Programs. Vol. 48, No. 3

doi: 10.1130/abs/2016SE-273849

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