See more from this Division: Gulf Coast Association of Geological Societies
See more from this Session: Gulf of Mexico Coastal Plain Paleontology
Abstract:
The larger size of Gosport mollusks must therefore be due to faster growth and/or longer lifespan. To assess life history trajectories and size-age relationships, we used sclerochronology and stable isotope geochemistry on three taxa common to the Gosport and neighboring formations. Stable isotope analyses of microsamples collected along the ontogenetic trajectory reveal seasonal temperature changes and hence provide a chronometer for growth. Data for the gastropod Agaronia indicate that Gosport individuals lived less than two years but attained sizes 4 to 5 times larger than those in the Lisbon and Moodys Branch Fms. Specimens of the bivalve Venericardia lived an average of 6 years, but those in the Lisbon and Moodys Branch Fms are only half as large as of those in the Gosport. Isotope data from the bivalve Nucula are still pending, but growth banding suggests much slower growth in individuals from the Lisbon and Moodys Branch Fms. We speculate that larger size and faster growth is the result of higher primary production during deposition of the Gosport Sand. Rapid growth is an expected ecophenotypic response to higher food availability.
See more from this Division: Gulf Coast Association of Geological Societies
See more from this Session: Gulf of Mexico Coastal Plain Paleontology