|Northeastern Section (45th Annual) and Southeastern Section (59th Annual) Joint Meeting (13-16 March 2010)|
|Paper No. 80-1|
|Presentation Time: 1:30 PM-5:35 PM|
THE RELATIONSHIP BETWEEN SEXUAL DIMORPHISM AND TAXON LONGEVITY IN FOSSIL AMMONOIDS: A ROLE FOR SEXUAL SELECTION IN EXTINCTION
STILL, Claire E. L., Department of Geology, College of William and Mary, Po Box 8795, Williamsburg, VA 23187, email@example.com and LOCKWOOD, Rowan, Department of Geology, College of William and Mary, P.O. Box 8795, Williamsburg, VA 23187|
Recent studies have suggested that the strength of sexual selection in modern birds can be linked to increased species extinction risk. If this is the case, this relationship may represent an example of species level selection, i.e., selection occurring at or above the species level. The fossil record provides an ideal opportunity to test this possibility over long timescales. The goal of this study is to investigate the relationship between sexual dimorphism (a proxy for the strength of sexual selection) and taxon longevity (a proxy for extinction risk) in ammonoids.
We compiled global data on the presence and absence of genus-level sexual dimorphism in Paleozoic and Mesozoic ammonoids from a recent literature compilation. We also compiled first and last global occurrence data from the Paleobiology Database and the biostratigraphic literature to calculate genus-level taxon durations. Additionally, we assessed survivorship across larger events, including the Cenomanian-Turonian extinction. The possible relationship between dimorphism and extinction risk was quantified by comparing taxon durations between 124 monomorphic and 122 dimorphic genera, ranging from Triassic to Cretaceous in age. Taxa that went extinct at the K/T boundary were eliminated from this analysis to avoid artificially truncating their durations. Preliminary results indicate no significant effect of sexual dimorphism on taxon survivorship, when the data are pooled across all genera. However, when we account for phylogenetic inertia, the presence of sexual dimorphism does appear to be positively correlated with increased extinction risk, at least in some superfamilies.
To explore this possibility in more detail, we are currently focusing on a single superfamily (Acanthocerataceae) and compiling data on microconch versus macroconch diameter in genera exhibiting sexual size dimorphism. This will allow us to assess the relationship between the degree of sexual dimorphism and taxon longevity. The resulting database is under construction and currently contains 65 macroconch and 78 microconch measurements from 31 species with 20 genera within this superfamily.
Northeastern Section (45th Annual) and Southeastern Section (59th Annual) Joint Meeting (13-16 March 2010)
General Information for this Meeting
|Session No. 80--Booth# 36|
Paleontology II, Mesozoic and Cenozoic (Posters)
Sheraton Baltimore City Center: International ABCDF
1:30 PM-5:35 PM, Tuesday, 16 March 2010
Geological Society of America Abstracts with Programs, Vol. 42, No. 1, p. 185
© Copyright 2010 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.