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The Plio-Pleistocene Pinecrest beds (Tamiami Fm.) of southern Florida rank amongst the most species-rich assemblages known from the Cenozoic macrofossil record. The tropical to subtropical fauna of the Pinecrest beds includes hundreds of mollusk species and subspecies (perhaps over 1,000), as well as diverse corals, bryozoans, and vertebrates. Some elements of the Pinecrest fauna are extant, but most species went extinct during one or more extinction pulses early in the Pleistocene. There was significant species turnover, but perhaps limited overall change in biodiversity relative to the present. Characterization of biotic change during this interval is important for understanding the evolution of the modern molluscan fauna of the southeastern United States but is unfortunately stymied by two major confounding factors. First, there are no natural exposures of the Pinecrest, and detailed sections have only been exposed in now-flooded quarries near Sarasota, Florida. Most samples from these and other quarries and canal cuts come from spoil piles, which often mix shells from multiple time intervals and habitats, limiting stratigraphic and ecological resolution for occurrence records. Second, the mollusks of the Pinecrest have not been comprehensively treated systematically and some elements of the macrofauna have likely been taxonomically over-split, leading to confusion and wariness among researchers about using published records in analyses. Conversely, the micromollusk fauna (<5.5 mm) has been understudied and many new species await description. Refining our understanding of this major regional turnover event is dependent upon a stable taxonomic foundation and supporting specimen occurrence data. Current estimates of diversity from literature and museum datasets do not closely align. Literature from the mid 1990s suggest over 550 species of gastropods and 250 species of bivalves in the Pinecrest beds, but numerous species have been described subsequently, the majority in the gray literature. In contrast to published tallies, over 1,000 and 400 names have been applied, respectively, to Pinecrest gastropods and bivalves in the collections the Florida Museum of Natural History, representing 140 families. Over 280 micromollusk species may also be present in the Pinecrest fauna. We have begun a project to comprehensively refine and substantiate these estimates of biodiversity to better characterize the Plio-Pleistocene turnover event(s) that led to the establishment of the modern fauna. Funding source: This research is supported by NSF DEB 2225014.
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LOOK ON THE FOSSIL RECORD OF TURRIDS, YE PALEONTOLOGISTS, AND DESPAIR!
The neogastropod clade Conoidea includes the familiar cone snails (Conidae) and 17 additional families, all but one of which (Cryptoconidae) are extant. There are over 5,000 extant species and 380 genera of Conoidea, all of which are venomous predators. Many conoideans other than Conidae and Terebridae (auger snails) are often called “turrids” and are often characterized by the presence of an indented “turrid notch” at the terminal edge of the shell's sutural ramp. Conoideans have a rich fossil record that extends to the Cretaceous, but a combination of hyperdiversity, subtle differences between species, often small shell size, and taxonomic complexity has resulted in them being little studied, despite their evolutionary success. We have begun to explore the fossil record of conoideans from the Plio-Pleistocene of the southeastern United States as part of a broader project to catalog and document the fossil records of all gastropod and bivalve species from this system. A newly developed database derived from literature and museum collections shows that nearly 200 species-group names have been applied to conoideans (excluding Conidae) from this system, fewer than 10 of which were described in the past 50 years. We present preliminary assessments of the Pliocene to Recent diversity patterns of individual subclades from the Southeast. Preliminary data from the Paleobiology Database demonstrate that occurrences assigned to the conoidean family Turridae from this study region are much less likely to be assigned to species than most other co-occurring mollusk families, with about 56% of occurrences assigned to a species. Online specimen data derived from the Florida Museum of Natural History similarly show that just under 50% of records from this system assigned to Turridae are also assigned to species. Because records unidentified to species are unevenly distributed among molluscan families, attempts to restrict analyses to only records which are well-resolved taxonomically may impact our overall understanding of biodiversity and ecology, especially when they result in the exclusion of species-rich clades. Our results highlight the importance of primary systematic research and museum collections for assessing important but understudied components of the biodiversity of fossil molluscan faunas.
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- Award ID(s):
- 2225014
- PAR ID:
- 10479901
- Publisher / Repository:
- Geological Society of America
- Date Published:
- Journal Name:
- Geological Society of America Abstracts with Programs
- Volume:
- 55
- Issue:
- 6
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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