217-7 Baby Shark DoDoDoDo: The Paleoenvironment of the Eutaw Formation in Northeastern Mississippi

Session: Paleontology, Paleoecology/Taphonomy

Presenting Author:

Authors:

Abstract:

The Eutaw Formation is a Late Santonian member of Mississippi’s northeastern Upper Cretaceous sediments. It is divided into two groups in Mississippi, the lower, unnamed or “typical” Eutaw and the upper Tombigbee Sand Member. The formation was deposited along the margins of the Western Interior Seaway as a product of Upper Zuni 3.0 sequence. 

Researchers investigated the depositional environment and paleoecology of both units through chemical composition analysis and the collection and identification of fossils, resulting in the construction of a complete faunal assemblage. This project ultimately provides further insight and clarity for future research in the area. It also further investigates the differences between the Tombigbee Sand Member and the Eutaw Formation proper to contextualize the changes in environment and fauna through time.

The collection was conducted in early June of this year as a part of the NSF funded Gulf Coastal Plain Ecology REU at the University of Southern Mississippi. Fossils and sediment were obtained at two specific locations, both near the city of Columbus, in Lowndes County, Mississippi, USA. Individual fossils were collected along with multiple bags of loose sediment. Sediment was sieved and observed under a dissecting microscope to differentiate microfossils, which were then sorted and identified. The chemical composition of the sediment was obtained using a Handheld X-Ray Fluorescence spectrometer. Organic matter content and Magnetic Susceptibility were also determined, with the latter utilizing a Bartsoft MS2B meter. 

The faunal assemblage of the sites seems to, for the most part, reflect the fauna identified in previous studies with the addition of some abnormal specimens. The chemical composition of the sites is similar in its silica and minor elemental composition but the sites vary significantly regarding iron and scandium content. Further investigation will determine the significance of these variations and its relation to the faunal assemblages described. This will ultimately provide a more comprehensive understanding of the Eutaw Formation’s fauna and depositional environment.

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

doi: 10.1130/abs/2025AM-6902

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