Geological Society of America

120 Paleontology V: Early Life

Tuesday, 30 October 2007
8:00 AM - 12:00 PM

ANCHORS AWAY: ANATOMY OF AN EDIACARAN SEA FLOOR DOMINATED BY PARVANCORINA

Paper number: 120-10
Program: Technical Sessions
Time: 10:15 AM – 10:30 AM

Authors

Mary L. Droser Presenting Author
University of California, Riverside, Riverside, CA
James Gehling
South Australian Museum, Adelaide, N/A
John Paterson
The University of New England, Armidale, N/A
Dennis Rice
South Australian Museum, Adelaide, N/A

Abstract

Excavation of 12 fossiliferous sandstone beds totaling over 100 square meters in the vicinity of Ediacara, South Australia, demonstrates a surprising level of heterogeneity between beds. Typically beds are dominated by one genus. With the notable exception of the clustering of Rugoconites, fossils do not generally show spatial patterns or orientation to current direction in life position.

On 7 square meter surface is dominated by nearly 100 Parvancorina associated with Dickinsonia spp., abundant tubes, and a spiral-like taxon all preserved on the base of the sandstone bed. The current direction is indicated by oriented frond stalks and tool marks all within 20 degrees of each other, and one partially overturned Dickinsonia. Orientation measurements of Parvancorina demonstrate a strong orientation consistent with tool marks and stalks. Interestingly, specimens of Parvancorina, interpreted to be in life position, appear to be predominantly oriented with their axis pointing into the direction of the current. This may have implications regarding a possible feeding strategy and ultimately taxonomic affinity.