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Population Dynamics of Dakoticancer overanus from the Pierre Shale, South Dakota.

Jones, AnnMarie
http://rave.ohiolink.edu/etdc/view?acc_num=kent1384772692

Abstract Details

2013, MS, Kent State University, College of Arts and Sciences / Department of Earth Sciences.
Fossil decapod species vary in number of specimens and degree of preservation. A collection from the Late Cretaceous Pierre Shale in South Dakota has yielded a large number of well-preserved specimens of Dakoticancer overanus from the vicinity of Mobridge, South Dakota. Collector Dr. Gale Bishop has published several articles on this collection of Dakoticancer overanus specimens. It is rare to find a collection this sizeable of a single species of crabs. Two hypotheses are possible; this collection is either a collection of molts or a community of whole dead crabs. The purpose of this study is to expand upon the work of Bishop and take a closer look statistically at the Dakoticancer overanus population. Studies of population dynamics have rarely been conducted on fossil decapods, whereas many such studies have been done on molluscan and brachiopod species. On this collection of specimens, measurements were taken of exoskeletal elements to compare size differences between males and females. Approximately eight hundred and forty specimens have been measured, and their sex has been determined. This sample population produced a normal size-frequency distribution, and therefore, the specimens are likely to be from one population. One of the most interesting aspects of this population is the discrepancy between numbers of males and females. There are 2.5 males for every female. It is difficult to analyze why such a discrepancy exists for an extinct species, but modern analogues are used to help understand factors that can influence the makeup of a marine invertebrate population. External morphology is the main way to decipher the sex of a fossil brachyuran. Characters to look for are placement of gonopores, the shape of the sternal plates, and the size of the pleon. Otherwise there is no other significant difference in morphology. Eight specimens are recognized as having both male and female morphology. Upon statistical analysis, it is proposed that this collection, including the intersex individuals, came from a single population. Thus, the eight intersex specimens do not belong to a different taxon. Additionally, two specimens from the Carnegie Museum of Natural History in Pittsburgh have been identified as intersex and one has a dwarfed gonopore. This collection was not included within the statistical analysis.
Carrie Schweitzer (Advisor)
Rodney Feldmann (Committee Member)
Joseph Ortiz (Committee Member)
125 p.
Geological; Paleoecology; Paleontology
Brachyura; Intersex; Decapoda; Population Dynamics; Gonopore, Crustacea, size-frequency distribution

Recommended Citations

Citations

  • Jones, A. (2013). Population Dynamics of Dakoticancer overanus from the Pierre Shale, South Dakota. [Master's thesis, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1384772692

    APA Style (7th edition)

  • Jones, AnnMarie. Population Dynamics of Dakoticancer overanus from the Pierre Shale, South Dakota. 2013. Kent State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1384772692.

    MLA Style (8th edition)

  • Jones, AnnMarie. "Population Dynamics of Dakoticancer overanus from the Pierre Shale, South Dakota." Master's thesis, Kent State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1384772692

    Chicago Manual of Style (17th edition)

kent1384772692
943
© 2013, all rights reserved.
This open access ETD is published by Kent State University and OhioLINK.