A semi-quantitative analysis of the distribution of conodonts in the maximum flooding deposits of the Lost Branch Cyclothem, "Latest Desmoinesian" midcontinent and Western North America

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dc.contributor.advisorLambert, Lance L.
dc.contributor.authorCanchola, Mary Katherine
dc.contributor.committeeMemberBirnbaum, Stuart J.
dc.contributor.committeeMemberGodet, Alexis
dc.date.accessioned2024-02-09T19:29:08Z
dc.date.available2024-02-09T19:29:08Z
dc.date.issued2014
dc.descriptionThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.
dc.description.abstractConodonts are common index fossils ranging from the Late Cambrian to the Late Triassic, and represent the phosphatic "teeth," "jaws," and "remains" of a soft-bodied animal that is analogous in outward appearance to an eel (Sweet, 1988). Most conodonts are comprised of 16-17 element types. They are concentrated in sedimentary deposits called cyclothems that represent rapid sea-level changes. The Nuyaka Creek Shale (Latest Desmoinesian) and its equivalents in the Lost Branch Cyclothem (Latest Desmoinesian) extend from the state of Texas to the state of Iowa, and correlate to time equivalent lithofacies in the Illinois, Paradox, and Great Basins of the Eastern and Western United States. For many decades it has been assumed that populations of conodont genera and species are evenly-distributed geographically across cyclothems; however, we are discovering that this may not be the case. The distribution of conodonts is dependent upon ecological and ontogenetic factors; these two factors affect the distribution and frequency of distribution of the individual species within the Lost Branch Cyclothem. Using quantitative analysis and paleoecological methods, a qualitative observation that conodont genera and species frequencies vary systematically from Texas to Iowa and Nevada to Utah was tested. The list of conodont fauna included Idiognathodus expansus, I. swadei, I. heckeli, I. n. sp. A., Swadelina neoshoensis, S. nodocarinata, S. recta, Neognathodus dilatus, N. expansus, N. n. sp. A., N. n. sp. B., Adetognathus lautus, Gondolella bella, G. denuda, G. ovata, Idioprioniodus conjunctus, Hindeodus minutus, Diplognathodus sp., Ellisonia sp., and juveniles ("idiognathodids" and "neognathodids"). Analysis of the recoveries disproved that conodont proportions of adults, subadults, and juveniles are equal, and instead suggests that unequal quantities represent a time-averaged population in which conodont elements accumulated over time. Analysis has also disproven that conodont taxa vary systematically across a geographic region; however, taxa are evenly-distributed in the study tract and systematic variation occurs on a species-level.
dc.description.departmentGeosciences
dc.format.extent197 pages
dc.format.mimetypeapplication/pdf
dc.identifier.isbn9781303919046
dc.identifier.urihttps://hdl.handle.net/20.500.12588/2914
dc.languageen
dc.subjectconodonts
dc.subjectcyclothems
dc.subjectDesmoinesian
dc.subjectLost Branch
dc.subjectPennsylvanian
dc.subject.classificationGeology
dc.subject.classificationPaleoecology
dc.subject.classificationParasitology
dc.subject.lcshConodonts -- United States
dc.titleA semi-quantitative analysis of the distribution of conodonts in the maximum flooding deposits of the Lost Branch Cyclothem, "Latest Desmoinesian" midcontinent and Western North America
dc.typeThesis
dc.type.dcmiText
dcterms.accessRightspq_closed
thesis.degree.departmentGeosciences
thesis.degree.grantorUniversity of Texas at San Antonio
thesis.degree.levelMasters
thesis.degree.nameMaster of Science

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