Publication Date
2019
Document Type
Thesis
Committee Members
Charles N. Ciampaglio, Ph.D. (Advisor); David A. Schmidt, Ph.D. (Committee Member); Stephen J. Jacquemin, Ph.D. (Committee Member)
Degree Name
Master of Science (MS)
Abstract
Chondrichthyan remains occur in abundance within a thin layer of limestone at the top of the Burlington Limestone at the point of the contact with the overlying Keokuk Limestone. This layer of rock, the "Burlington-Keokuk Fish Bed," is stratigraphically consistent and laterally extensive in exposures of the Burlington Limestone near its type section along the Iowa-Illinois border. Deposition of the fish bed occurred on the Burlington Continental Shelf carbonate ramp off the subtropical western coast of Laurussia during the Lower Carboniferous (Late Tournaisian; Osagean) due to a drop in sea level, although the specific mechanism(s) that concentrated the vertebrate fossils remain(s) unknown. Vertebrate remains found within the fish bed include abundant chondrichthyan (Holocephali and Elasmobranchii) teeth, spines, and denticles as well as bony fish and "Acanthodian" (stem chondrichthyan) remains. No studies of these remains or the fish bed itself have been published since 1905 (not including a 2010 Geological Society of America abstract); the total chondrichthyan diversity from the fish bed therefore remained relatively unknown until this study. The fish bed was sampled from two quarries (Nelson Quarry, Mediapolis, IA; Biggsville Quarry, Biggsville, IL). The limestone matrix was dissolved using standard methods for carbonate dissolution, and teeth were identified using original publications from the Burlington and Keokuk Limestones, the Handbook of Paleoichthyology, and appropriate literature. A diverse assemblage of chondrichthyans was recovered that represented at least fifteen genera and twenty three species as well as teeth that did not resemble anything yet described. Additionally, a compilation of all previous studies of the Burlington-Keokuk Fish Bed along with the current study was undertaken in order to create the most complete chondrichthyan faunal list yet reported for the fish bed. These results improve our understanding of chondrichthyan diversity on the Burlington Continental Shelf during the Osagean and will serve as a foundation for future studies of Osagean chondrichthyans both on the Burlington Continental Shelf and elsewhere around the globe.
Page Count
122
Department or Program
Department of Earth and Environmental Sciences
Year Degree Awarded
2019
Copyright
Copyright 2019, all rights reserved. My ETD will be available under the "Fair Use" terms of copyright law.
