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Phylogeny, diversity, and ecology of the ammonoid superfamily Acanthoceratoidea through the Cenomanian and Turonian

Mertz, David A.A.
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1494848155157068

Abstract Details

2017, Master of Science (MS), Bowling Green State University, Geology.
Both increased extinction and decreased origination, caused by rising oceanic anoxia and decreased provincialism, respectively, have been proposed as the cause of the Cenomanian Turonian (C/T) extinction event for ammonoids. Conflicting evidence exists for whether diversity actually dropped across the C/T. This study used the ammonoid superfamily Acanthoceratoidea as a proxy for ammonoids as a whole, particularly focusing on genera found in the Western Interior Seaway (WIS) of North America, including Texas. Ultimately, this study set out to determine 1) whether standing diversity decreased across the C/T boundary in the WIS, 2) whether decreased speciation or increased extinction in ammonoids led to a drop in diversity in the C/T extinction event, 3) how ecology of acanthoceratoid genera changed in relation to the C/T extinction event, and 4) whether these ecological changes indicate rising anoxia as the cause of the extinction. In answering these questions, three phylogenetic analyses were run that recovered the families Acanthoceratidae, Collignoniceratidae, and Vascoceratidae. Pseudotissotiidae was not recovered at all, while Coilopoceratidae was recovered but reclassified as a subfamily of Vascoceratidae. Seven genera were reclassified into new families and one genus into a new subfamily. After calibrating the trees with stratigraphy, I was able to determine that standing diversity dropped modestly across the C/T boundary and the Early/Middle Turonian boundary. I also found an increase in the percentage of genera becoming extinct in the Late Cenomanian, not a decrease in origination. Finally, I used Westermann morphospace to relate shell shape to ecology and mode of life. I found no decrease in morphospace occupation across the C/T boundary. More mobile modes of life expanded at this time. Morphospace occupation did drop across the Early/Middle Turonian boundary. All changes in morphospace occupation were driven by the family Vascoceratidae, suggesting this family was uniquely able to shift into novel modes of life in response to environmental change.
Margaret Yacobucci (Advisor)
Andrew Gregory (Committee Member)
Keith Mann (Committee Member)
110 p.
Geology; Paleontology
Cenomanian; Turonian; Ammonoid; Cephalopod; Evolution; Cretaceous; Cenomanian; Turonian; Acanthoceratoidea; Phylogenetics; Cladistics; Westermann morphospace; Morphology; Extinction; Origination; Diversity

Recommended Citations

Citations

  • Mertz, D. A.A. (2017). Phylogeny, diversity, and ecology of the ammonoid superfamily Acanthoceratoidea through the Cenomanian and Turonian [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1494848155157068

    APA Style (7th edition)

  • Mertz, David. Phylogeny, diversity, and ecology of the ammonoid superfamily Acanthoceratoidea through the Cenomanian and Turonian. 2017. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1494848155157068.

    MLA Style (8th edition)

  • Mertz, David. "Phylogeny, diversity, and ecology of the ammonoid superfamily Acanthoceratoidea through the Cenomanian and Turonian." Master's thesis, Bowling Green State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1494848155157068

    Chicago Manual of Style (17th edition)

bgsu1494848155157068
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This open access ETD is published by Bowling Green State University and OhioLINK.