Thesis
Two-dimensional landmark analysis of Spinocyrtid brachiopods of Euramerica during the Givetian
University of Iowa
Master of Science (MS), University of Iowa
Summer 2017
DOI: 10.17077/etd.a6y7mly2
Abstract
<p>Recent inquiry into the nomenclature of several species within Spinocyrtia has led to questions concerning name applicability and validity, particularly whether Delthyris granulosa and Spinocyrtia (Spirifer) granulosa are synonymous. This study utilized two-dimensional outline landmark analysis, a form of geometric morphometric analysis, to evaluate interspecific variation among these species. I took over a thousand photographs of over a hundred specimens of brachiopods belonging to the family Spinocyrtiidae. Ninety-six specimens originated from the Givetian outcrop belt of New York state, three were from northwestern Ohio, there was single Canadian specimen, and there was a single German specimen. The results from these analyses indicate that the mophospaces of Spinocyrtia (Spirifer) congesta, S. (Spirifer) granulosa, and S?. (Spirifer) marcyi are statistically (p < 0.05) distinct from one another.</p>
Details
- Title: Subtitle
- Two-dimensional landmark analysis of Spinocyrtid brachiopods of Euramerica during the Givetian
- Creators
- Alexander Patrick Layng - University of Iowa
- Contributors
- Kate Tierney-Cramer (Advisor)Charles Foster (Advisor)James Day (Committee Member)Christopher Brochu (Committee Member)Mary Kosloski (Committee Member)Brian Witzke (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Geoscience
- Date degree season
- Summer 2017
- DOI
- 10.17077/etd.a6y7mly2
- Publisher
- University of Iowa
- Number of pages
- ix, 46 pages
- Copyright
- Copyright © 2017 Alexander Patrick Layng
- Language
- English
- Description illustrations
- illustrations (some color)
- Description bibliographic
- Includes bibliographical references (pages 20-23).
- Public Abstract (ETD)
Brachiopods are marine invertebrates with dorsal and ventral valves comprising their shell. They are typically sedentary suspension feeders that range from continental shelf to abyssal depths. This study focuses on quantifying shape variance in the shell outlines of fossil brachiopods that lived over 380 million years ago in what is the present-day state of New York. At this time ocean covered much of what is now North America. This study was completed to determine whether Spinocyrtia congesta, S. granulosa, S. clintoni, S?. (Spirifer) marcyi are supported by the morphological species concept.
Morphology is the study of shapes. The morphological species concept uses body shape and physical features to characterize and recognize different species. Paleontologists utilize the morphological species concept as a method for identifying extinct organisms. Over an extended period of time as the result of evolutionary processes, populations of organisms may react to changes in environment with variations in behavior and morphology. These responses can result in anagenetic change, organisms that are a distinct from their ancestors.
This research shows that the shell outlines of Spinocyrtia congesta, S. granulosa, and S?. marcyi were statistically distinct from one another. This suggests that these are valid species; they refer to the lowest diagnosable taxonomic unit.
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9983776941002771
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