Paleontology Commons^™

A Record Of The Precambrian-Cambrian Transition In Sw Montana: A Late Neoproterozoic To Early Cambrian Stratigraphic Window, Fortunian Biostratigraphic Assemblage And Treptichnus Pedum, R. Reid Trippe

Graduate Student Theses, Dissertations, & Professional Papers

This study documents a Late Neoproterozoic through Early Cambrian stratigraphic record in the Humbolt anticline of southwestern Montana. The Precambrian-Cambrian transition includes a Fortunian-aged biostratigraphic trace-fossil assemblage with the ichnofossil Treptichnus pedum. The Humbolt anticline represents an inverted paleo-graben that exposes a stratigraphic window interpreted to be a record of rifting along the Cordilleran miogeoclinal margin, linked with the breakup of the Rodinia supercontinent. The graben subsided and captured sediment during late-stage rifting and final-stage dissociation along the rift margin. Its structural axis paralleled the rift margin. Sevier/Laramide orogenic thrusting inverted the graben into the Humbolt anticline. The Late …

Biodiversity And Distribution Of Benthic Foraminifera In Harrington Sound, Bermuda: The Effects Of Physical And Geochemical Factors On Dominant Taxa, Nam Le

Honors Theses

Harrington Sound, Bermuda, is a nearly enclosed lagoon acting as a subtropical/tropical, carbonate-rich basin in which carbonate sediments, reef patches, and carbonate-producing organisms accumulate. Here, one of the most important calcareous groups is the Foraminifera. Analyses of common benthic orders, including miliolids (Quinqueloculina and Triloculina spp.) and rotaliids (Homotrema rubrum, Elphidium spp., and Ammonia beccarii), are essential in understanding past and present environmental conditions affecting the island's coastal environment. These taxa have been studied previously; however, factors explaining their individual patterns of abundance in the Sound are not well detailed. The goal of this study is …

Geology Of Southeastern Nebraska, Robert Matthew Joeckel, Dana Divine, Leslie M. Howard, Kathleen Cameron, Michele M. Waszgis

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Discerning The Diets Of Sweep-Feeding Eurypterids Through Analyses Of Mesh-Modified Appendage Armature, Emily Samantha Hughes

Graduate Theses, Dissertations, and Problem Reports (ETD)

Eurypterids were a group of aquatic chelicerates that lived throughout most of the Paleozoic. While swimming eurypterids are generally considered to be active predators, the benthic stylonurine eurypterids appear to have had a mode of life similar to modern horseshoe crabs with the exception of two clades, the Stylonuroidea and the Mycteropoidea, both of which independently evolved modifications for sweep-feeding on their anterior appendages. Among extant suspension feeders, it has been shown that there is a linear correlation between the average spacing of feeding structures and prey sizes. This relationship was extrapolated to the sweep-feeding stylonuroid and mycteropoid eurypterids in …

Did You Know: Devonian, Daniel Childress

A with Honors Projects

This student's A with Honors project is a study on the Devonian period, with a table categorizing 24 species from the period and a poster with 10 lesser known devonian facts.

Scanning Electron Microscope Study Of Microstructure And Regeneration Of Upper Pennsylvanian Cladid Crinoid Spines, Hannah Smith, James Thomka

Williams Honors College, Honors Research Projects

The crinoid skeleton is characterized by a complicated, highly porous microstructure known as stereom. Details of stereomic microstructural patterns are directly related to the distribution and composition of connective tissues, which are rarely preserved in fossils. However, certain portions of the crinoid skeleton have never been studied with respect to stereomic microstructure. In particular, spines are common features on the crowns of many Paleozoic crinoids but had not previously been studied in detail with respect to stereomic microstructure. This study focused on pirasocrinid cladid crinoids, a common group with numerous identifiable crown spines, including spines on the arms and anal …

Ephemeral Gully Erosion Modeling And Surveying With Close-Range Digital Photogrammetry, M. A. Islam, C. Weerasekara, Y. Zhou, A. Y. Shesukov

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Exploring The Northwest Margin Of The High Plains Aquifer: Structure, Depositional History And Hydrogeology, Nebraska Geological Society Field Trip, Doug Hallum, Dennis O. Terry, Jr., Michael Leite, Jennifer Balmat

Conservation and Survey Division: Faculty and Staff Publications

The northwest portion of the High Plains Aquifer in Nebraska corresponds with the western Sandhills, Box Butte, Sioux and Dawes County tablelands, and the Nebraska Pine Ridge in northwest Nebraska. This field excursion will travel beyond the margins of the High Plains aquifer into the White River valley and onto the Oglala National Grasslands. These areas are not only rich in natural resources, but rich in history as well. While this excursion will explore earth history, depositional environments and a portion of the High Plains Aquifer, the authors encourage all attendees to take additional time to explore the cultural, military …

Morphometric Analysis Of Subfossil Macronycteris Spp. (Chiroptera: Hipposideridae) From Madagascar, Jamie Lynn Alumbaugh

Graduate Research Theses & Dissertations

Macronycteris bats are morphologically conservative between species but demonstrate intraspecific morphological variation between geographic locations and sexes. Two of the four living species of Macronycteris are found on Madagascar, where they are broadly distributed and demonstrate a trend in body size correlated with the latitudinal precipitation cline on the western side of the island. The presence of an extinct species, M. besaoaka, from Anhjohibe Cave in northern Madagascar suggests that Macronycteris was once more diverse, at least with respect to morphology. Since its description, taxonomic and phylogenetic revisions have reshaped our understanding of this genus. On Madagascar, these include the …

Structural Style And Stratigraphic Architecture Of The Northeastern Brooks Range, Alaska, Benjamin G. Johnson

Graduate Theses, Dissertations, and Problem Reports (ETD)

The Arctic Alaska–Chukotka microplate is a large Mesozoic–Cenozoic composite terrane that resides at the northern limit of the North American Cordillera. Although its Mesozoic origins are assuredly linked to the opening of the Amerasian Basin of the Arctic Ocean, its Paleozoic origins can be linked to at least three separate paleocontinents, including northern Laurentia, Baltica, and Siberia. Across the Arctic Alaska portion of the microplate, an internal, mid-Paleozoic suture zone presumably separates rocks of the North Slope subterrane (Laurentian affinity) from a collection of smaller subterranes in the southern Brooks Range and Seward Peninsula (Baltic affinity).

The mountains of the …

Death-Defying Morphologies: Mass Extinction And Disparity In The Order Harpetida, James Desmond Beech

Graduate Theses, Dissertations, and Problem Reports (ETD)

The trilobite order Harpetida has long been easily recognized but poorly understood. This study seeks to better understand the phylogenetic relationships within Harpetida, with a view towards using this group to explore the relationship between extinction intensity and disparity. The harpetid response to the Late Ordovician mass extinction is of particular interest. A discrete morphological character matrix was created from the formal descriptions of harpetids in the published trilobite literature, and refined using first-hand observations of harpetid fossils. The final matrix consists of 76 discrete characters, including 69 cephalic characters, three thoracic characters, and four pygidial characters. This matrix is …

Utilizing Radiolarian Assemblages To Track Changes In The Agulhas Current Through The Mid-Pleistocene Transition: Iodp Site U1479, William Alberto Bugbee

Graduate Research Theses & Dissertations

The objective of this study was to assess the radiolarian assemblage of the Agulhas Current at International Ocean Discovery Program Expedition 361, Site U1479 (the most westward site), through the Mid-Pleistocene Transition (MPT). Samples between 1,000 to 777ka were utilized to (1) characterize the radiolarian assemblage, (2) observe whether the radiolarian assemblage is sufficiently distinctive to help discern the occurrence of the MPT in the Southern Ocean, and (3) determine whether changes in the radiolarian assemblage reflect a change or changes in ocean currents that may have occurred during the MPT.

Over 300 radiolarian species from 15 different families were …