Author ORCID Identifier

https://orcid.org/0009-0008-9132-0953

Semester

Spring

Date of Graduation

2025

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

James Lamsdell

Committee Co-Chair

Kathy Benison

Committee Member

Kathy Benison

Committee Member

Dorothy Vesper

Abstract

Trilobites are a well-preserved group of arthropods, with a fossil record extending from the Cambrian to the end of the Permian. Abnormalities, such as injuries or teratological defects, have been observed and described in multiple individuals, although investigating how these abnormalities occur in populations has been largely overlooked.

One possible cause of abnormalities in marine arthropods is heavy metal pollution. Such metals can leave individuals more susceptible to teratological deformities and injuries, interfering with the molting and healing process. Here, methods for analyzing elemental composition and preservation of the trilobite cuticle were refined, finding that 30 μm thin sections are ideal for observing original and diagenetic structures in trilobite cuticles, and that μ-XRF has the ability to detect more trace elements deeper within the fossils when compared to FESEM-EDS. These updated methods were applied to see if heavy metal pollution led to the increased proportion of abnormal proetid trilobites from the Mississippian strata of Appalachia. Fossils from a road cut on Route 460, just outside Glen Lyn, Virginia were well preserved enough to derive meaningful elemental data from them, as there were no signs of recrystallization in petrographic thin section or SEM images. These fossils did not contain signs of heavy metal accumulation when analyzed with a μ-XRF, indicating that the abnormalities could have been a result of biotic causes, such as a genetic bottleneck that occurred as a result of the Kellwasser and Hangenberg events.

Download

Share

COinS