54 New Approaches to Old Fossil Collections

Material collected during the early history of paleontology conserves deep time ecosystems and remains available for study. We invite presentations of new analyses and interpretations of well-studied collections in the context of the broader history of the discipline.

Sunday, 19 October 2025
1:30 PM - 5:30 PM
HBGCC, 303AB

Elements of the modern molluscan fauna in the Plio-Pleistocene of the southeastern United States: Taxonomic practice or persistence?

Paper number: 54-11
Program: Technical Sessions
Time: 4:15 PM – 4:30 PM

Authors

Abstract

For over 200 years, paleontologists have applied the names of extant molluscan species to geologically young fossil material from the southeastern United States. This study system provides critical data about the evolutionary history of the modern gastropod and bivalve fauna of this region, which is today represented by over 2000 species based on a new analysis of GBIF data. While some extant species have long durations that extend back millions of years into the Pliocene and even Miocene, it is also likely that some names of extant taxa have been applied to fossil material in lieu of comprehensive monographic treatments of individual stratigraphic units. We explore the fossil record of extant species in this system using a taxonomically standardized, specimen-based dataset derived from the collections of the Florida Museum of Natural History. The complete fossil dataset contains nearly 123,000 occurrence records for almost 2,700 species of marine bivalves and gastropods, approximately a third of which are purportedly extant. Using a subset of these data, we compare Lyellian percentages for successively younger stratigraphic units in Virginia and North Carolina versus comparable units in southern Florida. Predictably, Lyellian percentages increase in successively younger units in both sequences but are higher in Late Pliocene and Early Pleistocene units in southern Florida than in the north. We ascribe this result in part to workers sometimes applying names of extant species to fossil material when monographs are not otherwise available. However, another possibility is that the southern end of the fauna was less impacted by Plio-Pleistocene climatic changes and had lower rates of extinction. This study informs our understanding of the timing and sequence of the modernization of the modern western Atlantic molluscan fauna and emphasizes that museum collections are critical to this research. This material is based upon work supported by the National Science Foundation under grant numbers 2525946 and 2225013.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412681

© Copyright 2025 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.