Thesis
Systematics of new early Silurian (Llandovery) trilobites from the Sexton Creek Formation, southeast Missouri
University of Iowa
Master of Science (MS), University of Iowa
Summer 2025
DOI: 10.25820/etd.008134
Abstract
Little work has been done on the Sexton Creek Formation, a fossiliferous limestone unitlocated in southeastern Missouri and southwestern Illinois. Only one species of trilobite, Dalmanites croneisi Ball and Delo, 1940, has previously been reported from the formation.
Recent conodont work has constrained the age of the Sexton Creek to Telychian, with the lower part possibly Aeronian. Current research primarily focuses on the systematics and taxonomy of a new trilobite fauna collected from a locality on the banks of Blue Shawnee Creek, Cape Girardeau County, southeastern Missouri. Ten species — all new — are present, with single species assigned to each of Anacaenaspis? (Odontopleuridae), Ceratocephalina (Odontopleuridae), Curriella (Encrinuridae), Daytonia (Dalmanitidae), Dekalymene (Calymenidae), Dicranopeltis (Lichidae), Exallaspis (Odontopleuridae), Failleana (Styginidae), Harpidella (Aulacopleuridae), and Lichas (Lichidae). The material is mostly disarticulated, but a
single articulated specimen of Exallaspis lacking librigenae, two cephala of Dekalymene, a cephalon of Ceratocephalina, and a thoracopygidium of Curriella are known.
The assemblage compares taxonomically with coeval faunas from the Jupiter Formation of Québec, the Brassfield Formation of Ohio, the Tegart Formation of British Columbia, the Attawapiskat Formation of Ontario, the Samuelsen Høj and Hauge Bjerg Formatioms of Greenland, the Whittaker Formation of the Northwest Territories, and the Newlands, Wood Burn, and Wether Law Linn Formations of Scotland.
Details
- Title: Subtitle
- Systematics of new early Silurian (Llandovery) trilobites from the Sexton Creek Formation, southeast Missouri
- Creators
- Andrew J. Studzinski
- Contributors
- Jonathan M Adrain (Advisor)Christopher A Brochu (Committee Member)Stephen R Westrop (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Geoscience
- Date degree season
- Summer 2025
- DOI
- 10.25820/etd.008134
- Publisher
- University of Iowa
- Number of pages
- x, 146 pages
- Copyright
- Copyright 2025 Andrew Studzinski
- Language
- English
- Date submitted
- 07/22/2025
- Description illustrations
- illustrations (some color), plates
- Description bibliographic
- Includes bibliographical references (page 133-146).
- Public Abstract (ETD)
The Sexton Creek Formation is a fossiliferous rock formation located in southeastern Missouri and southwestern Illinois. This formation is between 433.4 and 438.5 million years old, though recent work suggests it may be up to 440.8 million years old. Little trilobite work has been done it, as only one species of trilobite has been reported. This thesis describes seven new trilobite species from the Sexton Creek Formation, along with three other possible new species.
Other geologic formations from the same paleocontinent, Laurentia, similar age and similar trilobites as the Sexton Creek Formation include the Jupiter Formation of Qu bec, the Brassfield Formation of Ohio, the Tegart Formation of British Columbia, the Attawapiskat Formation of Ontario, the Samuelsen H j and Hauge Bjerg Formations of Greenland, the Whittaker Formation of the Northwest Territories, and the Newlands, Wood Burn, and Wether Law Linn Formations of Scotland.
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984948341002771
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