256-8 Investigating the Spatial and Temporal Distribution of a New Soft-Bodied Taxa from the Devonian Appalachian Basin Through Integrated Sedimentological, Geochemical, and Paleontological Techniques

Session: Life and Environments Through Time and Space: Multi-Record Approaches to Stratigraphic Paleobiology, Part I

Presenting Author:

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Abstract:

Any interpretation of the stratigraphic record must account for the uneven distribution of fossils in space and time. Although such inequalities can be caused by a number of parameters, one, oxygen availability, impacts both the ability of organisms to inhabit a given environment and their preservation potential. The redox state of ancient systems is typically evaluated using either paleontological assessments or geochemical redox proxies. However, geochemical proxies commonly used to determine features such as the extent of anoxia are limited in their ability to assess the portion of the redox ladder surrounding the oxic/anoxic boundary, or the zone in which many organisms with minimal oxygen requirements can still survive.  

Here we investigate the role anoxia may have played in the preservation of an undescribed group of soft-bodied discoidal fossils from the Middle Devonian, Givetian from the Appalachian Basin in central New York. We identified these fossils in an otherwise barren interval of the Spafford Member of the Ludlowville Formation, Hamilton Group. This interval is several meters thick and correlated across tens of kilometers between two sections, Sampson State Park (SSP) and Butlers Hollow (BH), as well as at a slightly younger site, Camp Summit Quarry (CSQ). To investigate paleoenvironments and sedimentological conditions, we used a combination of petrographic and geochemical techniques, including various paleoredox proxies and SEM analyses. Data from the two correlated sections, SSP and BH, is consistent with hypoxic (low-oxygen) conditions. This suggests that oxygen concentrations allowed for both the presence of these soft-bodied, inferred pelagic metazoans, while reducing enough to exclude typical shelled taxa and facilitate exceptional preservation. New data from CSQ will test whether hypoxic conditions are similarly associated with these soft-bodied fossils and refine correlations between these presumably discrete intervals. This will help determine both the full extent of these soft-bodied fossils during this time period and the conditions necessary to preserve them. Additionally, this will broaden our knowledge of local redox conditions in the Appalachian Basin during the Givetian, thus greatly increasing our understanding of how taphonomic windows facilitating exceptional preservation can help simplify correlation in the region. Additionally, this work increases our understanding of diversity during the lead into the Late Devonian Mass Extinction. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10202

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