Theses and Dissertations at Montana State University (MSU)
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Item A mess of rotten eggs from the Two Medicine Formation, Montana(Montana State University - Bozeman, College of Letters & Science, 2024) Tucker, Katherine Lydia; Chairperson, Graduate Committee: David J. VarricchioThe Two Medicine Formation of Montana is known for producing many dinosaur eggs in varying states of preservation. An unusual clutch of eggs MOR 11881 was recently found in the formation that exhibits some distinctive preservation features. The purpose of this research is to describe this clutch using multiple techniques to identify and better understand its taphonomic history. To do this the clutch was prepared by removing sediment from around the eggs, then examined using light microscopy, scanning electron microscopy (SEM), cathodoluminescence (CL), energy dispersive x-ray spectroscopy (EDX), and electron backscatter diffraction analysis (EBSD). Preparation uncovered eleven partially compressed ellipsoidal eggs in the clutch. Microscopy of the eggshell revealed that it is made of two structurally distinct layers. The lower layer at the base of the eggshell is here referred to as the blocky layer based on the blocky texture of the crystals in SEM images. This layer is sometimes interrupted by a phosphatic dark region. The second layer is the lobed layer found along the outer surface of the eggshell. It is characterized by lobes of blocky crystals surrounded by smaller radiating crystals. In addition to the eggshell the eggs also preserve a phosphatized eggshell membrane, two distinct types of pellets, large masses of collophane crystals and hyphae like structures. Unaltered eggshell is found in the sediment surrounding the clutch. The eggshell of the MOR 11881 clutch does not match any described ootaxon but is similar to eggshell found at the Egg Mountain quarry which was never identified. The unusual structure of the eggshell could be the result of multiple stages of alteration. Several structures in the eggshell including the lobes and the dark region are most likely the result of alteration. The presence of unaltered eggshell near the eggs indicates that the source of alteration was the decay of the eggs as recorded by their contents. This decay also produced the conditions necessary for the exceptional preservation of the eggshell membrane.Item Ichnology and sedimentology of the non-marine Frontier Formation (upper Cretaceous) of southwestern Montana(Montana State University - Bozeman, College of Letters & Science, 2023) Panasci, Giulio; Chairperson, Graduate Committee: David J. Varricchio; This is a manuscript style paper that includes co-authored chapters.The Frontier Formation of southwestern Montana (USA) is comprised of rocks assigned to the early Upper Cretaceous (Cenomanian- Santonian), and has recently yielded a notable fossil record, mostly comprised of dinosaur tracks and invertebrate trace fossils. This fossil record lays within a poorly understood period of the Upper Cretaceous, also known as the middle Cretaceous, valued as critical to understand the evolution of terrestrial ecosystems in North America at the end of the Mesozoic Era. This study aims to describe and analyze preservation and distribution of the Frontier trace fossils record. Twelve stratigraphic sections are measured and sedimentology, taphonomy, and stratigraphic framework described for the main fossiliferous sites. Sixty-five dinosaur tracks and associated invertebrate traces are described. Three tracks are further analyzed by combining anatomical characters and track morphological features to infer a more specific producer. Photogrammetry, tridimensional models, and color elevation maps are generated to document significant specimens and to map two excavated track sites. A concise description and classification of a freshwater turtle is also included to enhance paleoecological and paleodepositional reconstructions. A Coniacian age is provided for the Frontier Formation, main fossiliferous sites. Sedimentology and fossil record suggest the establishment of a rich ecosystem in alluvial plains and wetlands extending between the offshoots of the uplifting Rocky Mountains to the east and the Cody Sea to the east. Facies distribution across the southwest-northeast transect suggests that fossil distribution and preservation is mainly controlled by autogenic and allogenic processes seen in foreland basin systems. Tracks and invertebrate trace fossils preservation was likely favored by high sedimentation rates and variations of the ground water table. Dinosaur track assemblage is comparable to those reported in other middle Cretaceous formations of western North America and include derived hadrosauriform ornithopods, ankylosaurians, and theropods. The integration of body fossil data would suggest the presence of a fauna that included elements (i.e. Neurankylus sp.) shared with Campanian and Maastrichtian formations, suggesting that the Coniacian ecosystems across southwestern Montana was likely undergoing a process of provincialisms as seen in North America at the end of the Cretaceous.Item Structural control of the Norris Hot Springs and associated geothermal system(Montana State University - Bozeman, College of Letters & Science, 2023) Wafer, Mia Peyton; Chairperson, Graduate Committee: Andrew K. LaskowskiMany active and productive geothermal systems are structurally controlled, suggesting that certain structural configurations have higher potentials for geothermal energy. Analyzing potential productive geothermal wells is known as geothermal play fairway analysis (PFA). Identifying these high potential structural configurations is another way to locate geothermal systems without surface expressions, which represent an unquantified natural resource for geothermal energy. By studying geothermal systems with surface expressions, I move closer to being able to locate additional natural resources. The Norris Hot Springs, located in the foothills of the Tobacco Root Mountains, Southwestern Montana, presents a novel study area to test structural control on geothermal system development. I combine geologic mapping, UAV-based photogrammetry, zircon U-Pb geochronology, seismic data, and 3D geologic modeling to date and interpret the multistage development of local structures and their influence on the geothermal system beneath the Norris Hot Springs. A comprehensive structural model suggests the geothermal system associated with the Norris Hot Springs is hosted by a deep network of faults and fractures in Precambrian gneiss basement. A nearby fault system primarily comprised of high angle NNW-SSE trending normal faults, which often display pervasive alteration and polymetallic vein mineralization, likely connects surficial features with deeper reactivated Laramide-era structures. A primary goal of this study was to investigate the benefits of supplementing traditional field work with novel methods. Results from this study demonstrate the utility of combining geologic mapping, 3D modeling, structural analysis, 3D modeling and UAV surveys for geothermal exploration and constrain the timing and influence of local faulting on geothermal activity at the Norris Hot Springs.Item The kinematics and dynamics of rifting in south-central Tibet(Montana State University - Bozeman, College of Letters & Science, 2023) Reynolds, Elizabeth Aislin Nicole; Chairperson, Graduate Committee: Andrew K. Laskowski; This is a manuscript style paper that includes co-authored chapters.Southern Tibet is a unique location to study complex interactions between continental collision and extension, or stretching, of the Earth's crust which forms linear structures called rifts. The study of rifts is important because the rocks they expose can record thermal changes in the Earth's crust related to large-scale processes such as shifts in tectonic plates which occur over long timescales and are difficult to observe. Rifts also interact with topography, can influence river systems, and cause changes in rainfall distribution across a landscape by forming topographic drainage divides. Despite their importance, the kinematics and dynamics of rifting, or processes that occur during rift formation and evolution, are not well understood. This study uses field and radiometric dating techniques to investigate the shape, orientation, and timing of extension in southern Tibet by testing kinematic models for two classes of rifts: (1) Tibetan rifts which are defined as rifts that are >150 km in length and crosscut the Lhasa Terrane, and (2) Gangdese rifts that are defined as rifts <50 km long that are isolated within the high topography of the Gangdese Range. Evaluation of rift age across the Tangra Yumco rift and three Gangdese rifts suggests the TYC rift formed through the linkage of smaller normal fault segments into larger and longer structures over time, while Gangdese rifts may have relatively constant lengths. Additionally, interactions between rifts and contractional structures have likely influenced the evolution of topography and drainage patterns in southern Tibet for at least the past sixteen million years. To further investigate structural interactions, a broader compilation of thermochronology ages expands results to include another Tibetan rift, the Lunggar rift. Trends in the data reveal all samples from Gangdese rifts and Tibetan rifts that spatially overlap the Gangdese Range yield ages between ~28-16 Ma, whereas samples north of the Gangdese Range yield ages between ~12-4 Ma. I interpret these results to reflect Gangdese rift initiation at ~28 Ma in conjunction with, and perhaps balancing, uplift driven by the India-Asia collision, while young ages North of the Gangdese Range (~12-4 Ma) reflect extension along Tibetan rifts.Item First digital forelimb reconstruction and range of motion assessment of the late Cretaceous dinosaur Troodon formosus(Montana State University - Bozeman, College of Letters & Science, 2023) Serio, Michael Anthony; Chairperson, Graduate Committee: David J. VarricchioTroodon formosus (Troodon) is a theropod dinosaur from the Late Cretaceous of North America primarily known from fragmentary fossil material. Hypothesized to hunt small game, Troodon, like many theropods, may have actively engaged its forelimbs to aid hunting behavior. Furthermore, the complexity of preserved nests associated with Troodon suggest it had sufficient range of motion and dexterity to use its forelimbs to manipulate its eggs. Additionally, Troodon's evolutionary position as one of the closest groups to living birds could indicate important information about the evolution of the avian wing. However, no complete forelimb material has yet been found for Troodon, and as such a complete reconstruction and range of motion (ROM) estimate of its forelimbs has yet to be attempted. This study aims to address these hypotheses and shortcomings by leveraging recent digital modelling technology to create the first forelimb reconstruction and ROM for Troodon. To overcome preservation limitations, surface scans from multiple Troodon fossils housed in the Museum of the Rockies (Bozeman, Montana) were digitally combined to reconstruct most of a forelimb. From this model, digital articulation in the software package Maya was compared with physical articulation ROM methods using 3D printed copies of the forelimb. The maximum angle of allowed motion for each forelimb joint until bone-on-bone contact was assessed. Results show increased flexion over extension in Troodon's joints, consistent with closely related species. However, Troodon also shows higher manual extension than close relatives. The humerus is also shorter and stockier, showing mechanical specialization for strength vs speed, and convergent features with primitive theropod species. These ROM and morphological differences imply a deviation in hunting strategy or forelimb utility and a deviation from avian forelimb morphology. Total manual ROM results cannot confirm whether Troodon was able to grasp its eggs and small prey single-handed, but two-handed apprehension remains feasible. This study utilized digital and physical ROM methods, analyzing for the first-time specimens that would have been previously overlooked. These results shed light on both the foraging and reproductive behavior of Troodon and have implications for understanding the evolution of modern avian reproductive behavior and the dinosaur-bird transition.Item Change in provenance and sediment routing history of the Miocene-Pleistocene Bengal Fan, Indian Ocean using detrital zircon (U-Th)/He thermochronology(Montana State University - Bozeman, College of Letters & Science, 2023) Dixon, Timothy Spencer; Chairperson, Graduate Committee: Devon A. Orme; This is a manuscript style paper that includes co-authored chapters.The Ganges-Brahmaputra river system carries thousands of tons of sediment from the Himalaya each year to the submarine Bengal Fan within the Indian Ocean. Deposition of sediments to the fan has been ongoing since at least late-Oligocene time (Krishna et al., 2016), preserving a record of Himalayan tectonics and topographic evolution (Blum et al., 2018). IODP Expedition 354 (2015) collected 1.7 km of sediment core from the Bengal Fan to expand the record of Himalayan sediment routing (France-Lanord et al., 2016). Detrital zircon U-Pb data from core samples reflect five major tectonostratigraphic sequences from the Himalaya-Tibet Orogen (Blum et al., 2018). Age populations appear to vary temporally, suggesting change in erosion rates and sediment routing through time, especially apparent during the Pliocene-Pleistocene transition. This research uses detrital zircon (U-Th)/He thermochronology, double dating analyses, and sediment mixing model approaches to fingerprint changes in sediment routing and river deposition to the Bengal Fan. (U-Th)/He analyses are used to quantify rock uplift and exhumation experienced in the Himalayas, facilitating lag-time interpretations across Miocene-Pleistocene time. To interpret the Bengal Basin sink record, a compilation of mid to low-temperature thermochronology datasets across the Himalaya-Tibet orogen is presented for characterization of modern-day thermochronologic age signals. This database highlights orogen wide trends in cooling dates that show younging apatite/zircon (U-Th)/He and fission tracks in the frontal Himalaya and syntaxes, and a younging trend in 40Ar/39Ar dates towards the orogen center. Zircon (U-Th)/He analyses of Bengal Fan sediments deposited 6.20 - 0.13 Ma reveal cooling dates from ~0.28 + or - 0.03 - 540.15 + or - 6.13 Ma. Age populations vary greatly between Miocene-Pleistocene time, with notable loss of >23 Ma populations between Miocene-Pliocene time and increasing 5.3 - 23 Ma populations across the Pliocene-Pleistocene transition with decreasing depositional lag-times. Comparison of age populations to previously recorded cooling dates from the orogen reveal shifts from Brahmaputra to Ganges sources between Miocene-Pliocene time before reaching a mixed drainage signal in the middle Pleistocene. Observed shifts in sediment provenance are attributed to coupled tectonic-climatic forces with regional acceleration of exhumation in the Himalaya, onset of northern hemisphere glaciation and increased denudation of the frontal-Himalaya during Miocene-Pleistocene time.Item Addressing the state of Yellowstone National Park's geologic maps using traditional and novel approaches(Montana State University - Bozeman, College of Letters & Science, 2023) Kragh, Natali Ann; Chairperson, Graduate Committee: Madison MyersAccurate geologic mapping is especially important for public land, such as Yellowstone National Park, so land managers can mitigate safety risks, mindfully place infrastructure, and communicate scientific knowledge to the public. The geology of Yellowstone National Park (YNP) has been repeatedly mapped over the last century by multiple geologists with varying perspectives and mapping goals. The most recent efforts have resulted in a patchwork of twenty-one different scale maps (one 1:125,000, one 1:100,000, and nineteen 1:62,500). Presently, there exists significant promise of publishing a higher resolution, seamless map of YNP; however, it has become apparent that many of the current internal maps disagree along their shared boundaries. This study aims to address these discrepancies using both traditional and novel techniques and determine if mapping along boundaries is the best practice towards creating a seamless map. In total, 485 areas of disagreement, referred to here as boundary problems, were identified. During this study, 66 boundary problems were resolved. Each resolved boundary problem was aided by traditional mapping techniques (i.e., field mapping, field petrography, sample collection, and limited geochemistry and thin section work). However, some areas could not be addressed by field methods alone and required a more substantial analytical approach. Three "case studies" were chosen to highlight how geochemistry could aide in mapping in YNP: 1) a geochemical, textural, and age analysis of "dacite" units found throughout the north and northwestern portions of YNP and the Greater Yellowstone Region, 2) compiling a geochemical database to compare and correlate known rock units to unrecognized outcrops found in the field, 3) a novel technique using Pb isotopes in detrital plagioclase crystals from volcaniclastic units to establish a volcanic source for the units. These approaches resulted in varying success, but overall, lead to a better understanding of the work that needs to be done in YNP to publish an accurate, higher resolution geologic map. This work highlights the importance of reassessing older geologic maps and making necessary updates when the need is recognized, particularly along disagreeing shared boundaries using multiple techniques.Item Blackfoot traditional knowledge, bison drive lines, and geospatial analysis(Montana State University - Bozeman, College of Letters & Science, 2024) Edmo, Kendall Rae; Chairperson, Graduate Committee: David B. McWethy; This is a manuscript style paper that includes co-authored chapters.Bison drive lines provide material evidence of ancestral Blackfoot practices. The spatial dimensions of drive lines highlight a sophisticated understanding of bison-environment interactions and the strategic use of geographic landforms and environmental features to maintain a critical lifeway. Here we examine broad-scale landscape use patterns among prehistoric Blackfoot bison hunters on the Northwestern Plains through an analysis of a network of drive lines in traditional Blackfoot territory (US) using Geographic Information Systems (GIS) and previous archaeological and anthropological research. The findings of this study show that ancestral Blackfoot designed bison drive lines to be positioned in proximity to key landscape resources including water, forested areas, and wetlands and kettle lakes. This study builds on previous research that applies an Indigenous archaeological framework that incorporates ethnohistoric narratives and traditional knowledge to provide important context for understanding the relationship between ancestral Blackfoot, bison, and the cultural landscape. Examining the relationship between drive lines and landscape features helps advance our understanding of the Blackfoot knowledge system that has adapted and endured for millennia.Item Rethinking water conflict and cooperation: a re-analysis of interviews in Montana and an example study from the Big Hole River watershed(Montana State University - Bozeman, College of Letters & Science, 2024) Bjorklund, Erin Nicole; Chairperson, Graduate Committee: Sarah P. Church; This is a manuscript style paper that includes co-authored chapters.Climate change heightens the supply and demand imbalance for freshwater, increasing the potential for conflict between water users. However, conflict is not the only outcome, as water demands can also create space for cooperation. The Basins at Risk (BAR) scale is one of the most prominent numerical measurements for analyzing the level of conflict or cooperation in freshwater-related events reported in public news sources. However, few studies in the U.S. West and none within Montana have utilized this method and little has been done to investigate alternative applications of the BAR scale beyond news event analysis. Therefore, this study examines 1) water conflict and cooperation trends in Montana and 2) how interview data can contribute to nuanced understandings of water conflict and cooperation. The intensity and type of issue for water events in Montana were cataloged and analyzed in a re-analysis of 63 interviews conducted for the Montana Drought Vulnerability Assessment. Results revealed that from the perspective of Montanan water stakeholders, cooperation over water resources outweighs conflict, and low-intensity conflictive and cooperative events are more prominent. The re-analysis results informed the selection of an example study utilizing the BAR scale to analyze event data (n=314) and primary interviews (n=11) collected in the Big Hole Watershed, Montana. Event data was sampled from 7 Montana news sources between the years 2007 and 2023. Primary interviews were conducted in February, March, and April 2024 with a variety of stakeholders in the Big Hole River Watershed (e.g., anglers, ranchers, fishing guides, Big Hole Watershed Committee board members, Fish, Wildlife and Parks). These data show the value of including primary interviews in a study utilizing the BAR scale. Moreover, results from this study can help researchers and resource managers monitor and identify water conflict and cooperation, by showing a nuanced understanding of conflict and cooperation.Item Reconstructing large herbivore abundance and environmental interactions in postglacial North America(Montana State University - Bozeman, College of Letters & Science, 2023) Wendt IV, John Arthur Frederic; Chairperson, Graduate Committee: David B. McWethy; This is a manuscript style paper that includes co-authored chapters.Large herbivores drive critical ecological processes, yet their long-term dynamics and effects are poorly understood due to the limitations of existing paleoherbivore proxies. To address these shortcomings, long-term records of paleoherbivores were constructed by (i) applying new analytical techniques to existing bison fossil datasets; and (ii) examining fecal steroid data that characterize temporal changes in ungulate abundance and community composition. These paleoherbivore reconstructions were analyzed in relation to their environmental contexts to better understand herbivore-ecosystem interactions through time in three separate studies: First, spatiotemporal changes in postglacial bison distribution and abundance in North America were examined by summarizing fossil bison observations. Bison observations were compared with simulated climate variables in a distribution modeling framework to project probable bison distributions in 1000-year intervals from the Last Glacial Maximum to present in light of changing climatic drivers over time. Since the Bolling-Allerod Interstadial (14.7-12.9 ka) the geographic distribution of bison is primarily explained by seasonal temperature patterns. Second, Holocene records of bison abundance were compared to paleofire reconstructions spanning the midcontinental moisture gradient to determine the relative dominance of herbivores and fire as biomass consumers. Bison dominated biomass consumption in dry settings whereas fire dominated consumption in wetter environments. Historical distributions of herbivory and burning resemble those of Sub-Saharan Africa, suggesting a degree of generality in the feedbacks and interactions that regulate long-term consumer dynamics. Third, the utility of fecal steroids in lake sediments for reconstructing past herbivore abundance and identity was tested by (i) characterizing the fecal steroid signatures of key North American ungulates, (ii) comparing these signatures with multiproxy data preserved in lake sediments from the Yellowstone Northern Range, and (iii) comparing influxes of fecal steroids over time to historical records of ungulate biomass and use. Bison and/or elk were abundant at Buffalo Ford Lake over the past c. 2300 years. Ungulate densities in the watershed were highest in the early 20 th century and likely contributed to decreases in forage taxa and possibly increased lake production. These results demonstrate long-term ecological impacts of herbivores and highlight opportunities for continued development of paleoherbivore proxies.