23 D15. Paleontology (Posters)

Friday, 20 March 2020
1:30 PM - 5:30 PM
Grand Ballroom A–D

COMPARISON OF NON-LETHAL PREDATORY TRACES IN RECENT AND FOSSIL SAND DOLLARS

Paper number: 23-30
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Non-lethal predation by fish and other organisms may result in marginal traces (bite marks) on the ambitus of an echinoid’s test in modern environments. Traces comparable to those found in Recent echinoids are also observed in fossil specimens. Although these traces can provide insight into biotic interactions involving both Recent and fossil echinoid communities, they are underexplored. In this study, we characterize non-lethal marginal traces on both live-collected and fossil echinoids. The live-collected specimens (n=68) are from the shallow shelf of the northern Gulf of Mexico (Apalachee Bay area, Florida) and include two species: Encope michelini and Clypeaster subdepressus. We examined fossil echinoids (n=86) including the species Encope aberrans and Clypeaster sunnilandensis reposited in the Invertebrate Paleontology Division at the Florida Museum. All fossil specimens are from the upper Pliocene Intracoastal Formation. They are congeneric to the live-collected echinoids and have been collected from localities in the same geographic area (Apalachee Bay area, Florida).

Non-lethal marginal traces were identified in the live-collected specimens. Fossil echinoid tests were screened for similar morphological traces and interpreted as non-lethal predatory traces if matching the morphological characteristics of modern traces. There appears to be species selectivity in both Recent and fossil specimens, where traces are more frequently observed on flatter sand dollars (Encope spp.) and rare on Clypeaster spp.

We aim to expand this study by carrying out an Elliptical Fourier Analysis using both live-collected and fossil echinoids, an approach that should allow for a more rigorous comparison of trace morphology between fossil and Recent echinoids. The results should enhance our ability to recognize non-lethal predatory traces in fossil and subfossil echinoid tests and, ultimately, help us to develop a novel proxy for studying the fossil record of non-lethal predation on echinoids. This study is part of a larger project, which aims to improve our understanding of non-lethal predation and the relationship between the predators causing the traces and their echinoid prey.

Geological Society of America Abstracts with Programs. Vol. 52, No. 2

doi: 10.1130/abs/2020SE-345130

© Copyright 2020 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.