Paleontology Commons^™

Enhancing Our Understanding Of Ancient Oceans Through The Investigation Of Molybdenum Behavior Under Sulfidic Conditions, Rachel Faye Phillips

Open Access Theses & Dissertations

The most abundant trace metal in the ocean today, molybdenum (Mo), exhibits distinct behavior in oxygenated water, where it remains predominantly dissolved, compared to euxinic (i.e., oxygen-free and sulfidic) water, in which it is sequestered into the sediment. This dissimilar behavior allows us to use Mo concentrations and isotopic compositions in sediment to reconstruct marine oxygenation conditions throughout geologic history. However, Mo sequestration mechanisms under euxinic conditions remain unresolved, which limits the accuracy and precision of reconstructions made using Mo signatures in the rock record. For my doctoral research, I experimentally investigated abiotic and biotic Mo sequestration mechanisms under various …

Utilizing Phylogenetic And Geochemical Techniques To Examine Echinoderms Through Time, Maggie Ryan Limbeck

Doctoral Dissertations

Understanding biotic changes through Earth’s history has been the goal of paleobiology since the inception of the field. Advances in science and technology have progressed allowing us to reassess old questions and new questions that could have not been addressed without these new methods. Echinoderms (sea stars, sea urchins, etc.) appear in the fossil record during the early Cambrian and are still abundant in marine ecosystems today. This persistence through time has made echinoderms model organisms to answer questions about Earth’s past and present. Despite this role as a model organism there are many questions that remain with respect to …

Stable Carbon And Oxygen Isotopes Of Early Silurian Pentameride Brachiopods From Québec, Ontario, And Nunavut, And Paleoenvironmental Implications, Jordan N. Siewnarine

Electronic Thesis and Dissertation Repository

Analysis of low-Mg calcite brachiopod shells for δ¹⁸O and δ¹³C signatures provide quantitative independent geochemical data for paleoenvironmental interpretations. We analyzed 59 brachiopod shells from lower Silurian carbonate rocks of Anticosti Island, the Hudson Bay Lowlands and Niagara regions for spaciotemporal isotopic trends for the early Silurian. Screening tests using scanning electron microscopy, cathodoluminescence and trace element analysis demonstrate exceptional preservation, suggesting retention of primary isotopic values.

δ¹³C and δ¹⁸O values of shells range from 0.2‰ to 2.9‰ and -6.9‰ to -4.3‰ (VPDB), respectively. Temporally, increases in δ¹³C and δ …

Stable Isotope Analysis Of A Platecarpus Tympaniticus (Squamata, Mosasauridae) With Actinocamax Sternbergi (Mollsuca, Belemnoidea) Reveals Possible Endothermic Thermoregulation, Mitchell Lukens

Master's Theses

Mosasaurs, ancient marine reptiles, dominated the late Cretaceous oceans. However, their ecological success is a contentious topic. Were they ectothermic, like their modern relatives the varanid lizards? Or endothermic like extant marine mammals? Stable isotopes can reveal temperature and physiological variances within skeletons, but do not differentiate between body temperature and ambient environmental temperature. A rare mosasaur specimen from the Smoky Hill Chalk of a partial, articulated Platecarpus tympaniticus with stomach contents of belemnites provides a possible direct temperature contrast between predator and prey. The belemnites, related to modern coleoids, are identified as Actinocamax sternbergi. These animals possessed body …

Stratigraphic Analysis Of The Capps Limestone In The North Norton Oil Field In Runnels County, Texas, William Thompson

Electronic Theses and Dissertations

The Desmoinesian (Middle Pennsylvanian) Capps Limestone Member of the Mineral Wells Formation is a carbonate reservoir located in North Central Texas. It consists of interbedded limestone, sandstone, and shale units. Much of the Capps Limestone exists in the subsurface of Brown, Coleman, Runnels, Coke, Nolan, and Taylor counties, however, the Capps Limestone outcrops on the surface in Brown, Eastland, and Palo Pinto counties.

The cored interval from Runnels County was deposited in a marginal marine environment during the Middle Pennsylvanian Period. Although the Capps Limestone was first described in the 1890s, there is still much to be discovered about its …

Analyzing Weathering Patterns In Modern And Paleolake Deposits Of Tecopa, California: Implications For The Detection Of Paleolakes On Mars, Jason Benjamin Carman

Theses and Dissertations

This study focuses on two stratigraphic sections from the Tecopa paleolake and samples from the modern Tecopa and Amargosa River basins as a terrestrial analogue to Martian paleolakes. Previous work shows that the later stages of Pleistocene Lake Tecopa were highly alkaline and saline due to evaporation, which led to the formation of authigenic lacustrine minerals such as zeolites, clays, and precipitates that are potentially similar to Martian paleolakes. Paleolakes can provide information on past aqueous processes, such as the changes in the hydrologic cycle that a particular area experienced over the lifespan of a lake on Earth or Mars. …

Palynology And Paleoclimatology Of The Chicxulub Impact Crater In The Early Paleogene, Vann Smith

LSU Doctoral Dissertations

At the end of the Cretaceous Period, a large bolide impacted the Earth and formed the Chicxulub impact crater in the Yucatán Peninsula, Mexico. In 2016, International Ocean Discovery Program (IODP) Expedition 364 Site M0077 drilled into the buried peak ring of the crater, recovering a marine Paleocene to early Eocene post-impact section deposited on top of the impact breccia. Palynological analysis of 195 samples from the post-impact section has yielded the first pre-Holocene vegetational record from inside the Chicxulub impact crater and the first palynological record of the recovery of life following the end-Cretaceous mass extinction from inside the …

Three Centuries Of Vegetation Change In The William & Mary College Woods Reconstructed Using Phytoliths, Timothy Terlizzi

Undergraduate Honors Theses

The College Woods, west of William & Mary’s campus, consists of ~900 acres of protected southern mixed hardwood forest. The woods surround Lake Matoaka, a former millpond established in ~1700. Despite the rich history of the area, little is known about how the dominant vegetative landcover has shifted over the last 300 years. This study set out to quantify the modern vegetation within the College Woods via the phytolith assemblages within the soil and identify shifts in the assemblages since the creation of Lake Matoaka and whether these changes are distinct from the vegetation that existed in the area before …

Diversity – Independent Factors Predict Elevated Extinction Rates, Dustin Perriguey, Corinne Myers, Jason Moore, Louis Scuderi

Earth and Planetary Sciences ETDs

Multiple linear regression was used to determine the relationships between diversity-independent factors (i.e., abiotic, climatic) 2, 5, and 10 Myrs-prior to the most elevated Phanerozoic extinctions. We constructed five abiotic variables from Phanerozoic proxy records1–5 to compare to extinction rates: mean temperature, temperature instability, carbon cycle instability, continental weathering rates, and habitat instability. All three models were statistically significant (P < 0.05) and explained > 70% of the variation in Alroy’s6 three-timer generic extinction rates. However, the 2 Myr-prior model explained the most variance in extinction rates and had the most predictive power, based on adjusted and predictive R2 (~ 72% and 41%, respectively). Carbon …

Reconstructing Surface Water Carbonate Ion Concentration Changes In The Eastern Equatorial Pacific Across Glacial Transitions, Lenzie Gail Ward

OES Theses and Dissertations

Today, the eastern equatorial Pacific (EEP) plays a critical role in the global CO₂ budget as a major source of CO₂ to the atmosphere, but recent studies suggest the region may shift to a sink for atmospheric CO₂ under different climate states. Here, I focus on two transitional periods, the last deglaciation (25 kyr to present) and last glaciation (the Marine Isotope Stage (MIS) 5a-4 transition, 96 to 60 kyr), to investigate how the carbon system in the EEP responds to major climate changes. I measured B/Ca ratios in the planktic foraminifera Globigerina bulloides from core MV1014-17JC …

Microbe-Mineral Interactions During Exceptional Fossil Preservation, Stromatolite Formation, And Desert Varnish Growth, Michael Strange

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Ediacaran to Cambrian Deep Spring Formation consists of mixed carbonate-siliciclastic strata which contain an increasingly complex and biogeographically important biota. Past investigations of the Deep Spring Formation at Mt. Dunfee, Nevada, explored the highly diverse microbialite reefs consisting of a wide range of stromatolite morphologies which exerted significant control on local sedimentation and topography. Early investigations also documented the biomineralizing metazoan Cloudina (an Ediacaran index fossil). However, recent exploration of the area has resulted in the discovery of several new metazoan fossil communities consisting of a diverse assemblage of Ediacaran soft-tissue tubicolous vermiforms (tube fossils) similar to Cloudina. The …

Assessing Diagenetic Conditions In The Late Triassic Chinle Formation Through Petrographic And Geochemical Analysis Of Phytosaur Teeth, John Fortner

Earth Sciences Theses and Dissertations

The Upper Triassic (Norian; ~227-208 Ma) Chinle Formation of Petrified Forest (PeFo) National Park was deposited during a time of major tectonic breakup and profound changes in atmospheric circulation and faunal compositions. Little has been done however to assess whether surficial paleoenvironmental trends related to deterioration of the Late Triassic Megamonsoon resulted in similar trends in the early diagenetic environment. Here, we use phytosaur tooth dentin as a proxy for diagenetic conditions in the Chinle of PEFO, as its greater susceptibility to chemical alteration relative to enamel makes it an excellent substrate from which changing diagenetic conditions may be studied …

Provenance And Maximum Depositional Age Analysis Of The Moenave Formation Using Detrital Zircon U-Pb Geochronology And Sandstone Petrography, Asher Rea Boudreaux

Graduate Theses and Dissertations

In southwestern Utah and northeastern Arizona, Moenave Formation (latest Triassic(?)-Jurassic) is bracketed by well-studied Mesozoic units extensively sampled for detrital zircon geochronology and is poorly documented in regard to provenance, representing an important gap in knowledge. The Moenave Formation provides a unique opportunity to employ detrital zircon U-Pb geochronology and sandstone petrography relevant to completing the paleogeographic, evolutionary, and climatic story of the region. This study aims to characterize the sedimentary provenance of the Moenave Formation and to identify, or at least improve constraints on, the stratigraphic position of the Triassic-Jurassic boundary (TJB) and placement of the end-Triassic extinction (ETE), …

Constraining The Oxygen Values Of The Late Cretaceous Western Interior Seaway Using Marine Bivalves, Camille H. Dwyer

Earth and Planetary Sciences ETDs

The Western Interior Seaway (WIS) remains an oceanographic enigma, including its circulation, similarity to the open ocean, and the fidelity of geochemical proxies to reconstruct paleoenvironments. Across the late Campanian and early Maastrichtian I test whether: 1) the WIS had unique δ¹⁸O_VPDB compared to other marine settings, 2) increasing oceanographic restriction changed the stable isotope composition, and 3) biases, e.g., taxonomy or diagenesis, influenced stable isotope compositions. Results indicate distinct δ¹⁸O_VPDB in the WIS compared to other marine settings. δ¹⁸O_VPDB values were stable through time, suggesting insignificant oceanographic restriction and a …

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 …

Stable Isotope Geochemistry Of Bioapatite, Amanda E. Drewicz

Boise State University Theses and Dissertations

The Cenozoic Era was a time period where dynamic shifts in climate created for both warm-wet greenhouse environments of the mid-Miocene Climatic Optimum (MMCO), and cool-dry, glacial periods of the late Pleistocene. The Cenozoic is close to our own time period, and although past climate reconstructions cannot be used as direct analogs for future climate change, understanding previous environmental responses can help inform policy surrounding future climate change. Presented here are climate reconstructions of the interior western United States, from two different geologic time periods. Each had a different climate, that differed greatly from modern day environments. The use of …

Evaluating Stable Isotope And Geochronologic Techniques For Paleoclimate Reconstruction: Case Study Of The Santa Cruz Formation, Argentina, Robin B. Trayler

Boise State University Theses and Dissertations

Stable isotope analysis has become the method of choice for many studies investigating the paleoecology and paleoclimate of fossil mammal faunas. While organic tissues (collagen, keratins, proteins) persist for < 10⁵ years highly mineralized tooth enamel is resistant to alteration and degradation and faithfully preserves its isotopic composition for millions (> 10⁶) years. Reconstructing past climates from these records relies on both understanding both micro-scale mechanisms of isotope incorporation into individual teeth, and macro-scale changes in isotope compositions over hundreds of thousands or millions of years. In this dissertation I address three questions.

First, how does the geometry and …

The Geochemistry And Mineralogy Of Surface Hydrothermal Alteration At Nesjavellir, Sw Iceland, Chase Glenister

Theses and Dissertations

Abundant sulfates have been detected by the Mars Exploration Rover Spirit in the Columbia Hills of Mars, consistent with extensive alteration of basalt by hydrothermal processes. This study uses Iceland’s Nesjavellir geothermal system as an analogue for Columbia Hills hydrothermal alteration. This terrestrial site is home to a variety of acidic and near-neutral waters that are actively altering the Mars-like basalt of host volcano Mt. Hengill. Hydrothermal features heated by H2S gas and phase-segregated steam created oxidizing acid-sulfate conditions at the surface with pH values varying between 3.0 and 2.0 and near-boiling temperatures. Mobilization of cations (FeO, MgO, CaO, Na2O, …

Cretaceous Dinosaurs And The World They Lived In: A New Species Of Ornithischian Dinosaur From The Early Cretaceous (Aptian) Of Texas, Reconstruction Of The Brain Endocast And Inner Ear Of Malawisaurus Dixeyi, And Reconstruction Of The Paleoclimate And Paleoenvironment Of Cretaceous Terrestrial Formations In Texas And Oklahoma Using Pedogenic Minerals, Kate Andrzejewski

Earth Sciences Theses and Dissertations

Material from over thirty individuals of a new ornithopod was recovered from the Proctor Lake locality in the Twin Mountains Formation (Aptian) of north-central Texas. This material includes various ontogenetic stages, providing insight into the growth patterns of this species. The new ornithopod is recovered basal to Iguanodontia, but more derived than Hypsilophodon foxii. The presence and morphology of 4 premaxillary teeth along with a combination of both basal and derived characters distinguish this taxon from all other ornithopods.

A braincase of the Cretaceous titanosaurian sauropod Malawisaurus dixeyi was CT scanned and a 3D rendering of the endocast and inner …

When, How, And Why Did The West Antarctic Ice Sheet Retreat In The Ross Sea Since The Last Glacial Maximum Using Foraminiferal And Porewater Geochemistry, Matthew Decesare

LSU Doctoral Dissertations

The Antarctic Ice Sheets (AIS) began to retreat from their Last Glacial Maximum (LGM) position sometime after 19,000 years ago. However, the corrosive waters circulating around Antarctica has prevented the recovery of radiocarbon-dateable material, hindering the development of deglacial chronologies. During Expedition NBP1502B to the eastern Ross Sea, an unprecedented quantity of fossil foraminifera and bivalves were recovered. Radiocarbon-dated specimens have been used to constrain the timing of West-AIS retreat from Whales Deep basin and Ross Bank. Whales Deep samples show that the WAIS retreated from its LGM position on the continental shelf edge by 14,700 ± 400 calibrated radiocarbon …

Micropaleontology And Isotope Stratigraphy Of The Upper Aptian To Lower Cenomanian (~114-98 Ma) In Odp Site 763, Exmouth Plateau, Nw Australia, Ali Alibrahim

Masters Theses

The biostratigraphy and isotope stratigraphy of the upper Aptian to lower Cenomanian interval including oceanic anoxic events OAE1b, 1c and 1d are investigated in ODP Site 763, drilled on the Exmouth Plateau offshore northwest Australia. Benthic foraminifera suggest that Site 763 was situated in outer neritic to upper bathyal water depths (~150-600 m). OAEs of the Atlantic basin and Tethys are typically associated with organic carbon-rich black shales and δ¹³C excursions. However, OAEs at this high latitude site correlate with ocean acidification and/or pyrite formation under anoxic conditions rather than black shales. Ocean acidification maybe responsible for sporadic …

The Stratigraphic Position Of Fossil Vertebrates From The Pojoaque Member Of The Tesuque Formation (Middle Miocene, Late Barstovian) Near Española, New Mexico, Garrett R. Williamson

Electronic Theses and Dissertations

The stratigraphy of the Pojoaque Member of the Tesuque Formation near Española, NM is not well understood. This region, during the Middle Miocene, represented a dynamic alluvial fan-fluvial-lacustrine environment within the Española Basin while the Rio Grande Rift was active. Cavazza (1986) identified two paleodrainage systems (lithosome A, basin-margin facies and B, basin-floor facies) by means of sandstone and conglomerate petrology, paleocurrent, and sedimentary facies analyses. After x-ray diffraction analyses of claystones within lithosome B, mordenite was discovered, which is a zeolite mineral commonly found within volcanic rocks. This is significant because the presence of mordenite confirms Cavazza’s (1986) conclusion …

Testing Of The Late-Ordovician Pre-Gice Warm Water Carbonate Hypothesis In Alabama, Brandon Euker, Stacey Law

Senior Honors Projects, 2010-2019

The Guttenberg Carbon Isotope Excursion (GICE) (uppermost Sandbian-lower Katian, Late Ordovician) has been suggested to represent the transition from a Cambrian-Ordovician greenhouse world to Late Ordovician icehouse world. This transition is thought to coincide with a proposed shift from deposition of warm water carbonate rocks to cool water carbonate rocks in the North American midcontinent. We used oxygen isotopes (d¹⁸O) of conodonts to test the idea that the rocks below the GICE interval represent a consistently warm environment. Conodonts were isolated from samples of the Chickamauga Group collected at the Tidwell Hollow section in Blount County, AL, from …

Climate, Ecology, And Human Evolution During The Plio-Pleistocene, Scott Adam Blumenthal

Dissertations, Theses, and Capstone Projects

A major goal of paleoanthropology is to identify the selective pressures associated with hominin biological and behavioral evolution, yet establishing cause-effect relationships between climate, ecology, and human evolution remains problematic. This dissertation seeks to investigate hominin paleoecology in eastern Africa by reconstructing aspects of climate and ecology using stable isotope analysis.

The first part of this dissertation is focused on the ecology of primates and hominins. Modern tropical African ecosystems provide a useful model for understanding the ecological correlates of isotopic variation in the fossil record, and living primates provide a useful model for understanding the ecological significance of isotopic …

Regional Geochemical Mapping Of The Superior Upland Province; Ichnology Of The Cretaceous Mesilla Valley Formation, Cerro De Cristo Rey; A New Ichnospecies Of Cardioichnus From The Cretaceous (Albian) Of New Mexico; A Pedagogy For The Cerro De Cristo Rey Tracksite; Walking In The Footprints Of Dino, Eric J. Kappus

Open Access Theses & Dissertations

This is a multi-disciplinary study that covers a variety of geoscience topics on both international borders of the continental United States. This Dissertation is the product of several separate investigations. First is a report on the landscape geochemistry of the Superior Upland Province of Minnesota, Wisconsin, and Michigan, with regional maps of 37 chemical elements interpreted in terms of bedrock, glacial reworking, and anthropogenic influence. The next 2 sections are reports on the invertebrate ichnology of the Cretaceous Mesilla Valley Formation at Cerro de Cristo Rey, including the proposal of a new ichnospecies of echinoid resting trace, Cardioichnus biloba nov. …

Oceanographic Controls On The Expression Of Cretaceous Oceanic Anoxic Events In The Western Interior Sea, Christopher M. Lowery

Doctoral Dissertations

The Cretaceous Period (145-66 Ma) was a time of elevated global temperatures superimposed on fluctuating climate regimes and repeated biotic turnover. It recorded several major perturbations of the carbon cycle, characterized by widespread deposition of organic-rich black shale and benthic and photic zone dysoxia to euxinia, termed oceanic anoxic events (OAEs). The Cenomanian-Turonian OAE2 and the enigmatic Coniacian-Santonian OAE3 are well-preserved in the Western Interior Sea (WIS) of North America. The expression of these OAEs in the WIS differs both from each other and from contemporaneous open-ocean sections. Despite decades of research, questions remain about the role of oceanographic parameters …

New Early Miocene 40ar/39ar Ages For Nakwai, Northwest Kenya, Africa, And Paleontological Analysis Of Meroehyrax Kyongoi Dentition, Dawn Elena Reynoso

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nakwai is a fossiliferous region in the Turkana Basin of northwestern Kenya. Until recently the only ages for the Nakwai formation were based on biostratigraphic correlation with Losodok; a late Oligocene site located to the north of Nakwai. The new 40Ar/39Ar ages in this study range from 23 Ma to 15 Ma and constrain the upper portions of the Nakwai section to the early Miocene. These ages make it the only securely dated fossil locality in the region that represents the earliest Miocene; all of the other early Miocene fossil localities date back to ~20 Ma or younger. The time …

Gastrointestinal Microbial Diversity And Diagenetic Alteration Of Bone From The American Alligator (Alligator Mississippiensis), Sarah Wheeler Keenan

Doctoral Dissertations

One of the most challenging questions in paleobiology is how bone transforms from a living tissue into a fossil. In life, the gastrointestinal tract microbiome of an animal promotes host health. But, in death, these microbial communities, as well as soil communities, begin to degrade tissue, including bones. Using the American alligator from coastal wetland habitats as a model system, the gastrointestinal tract microbiome was found to contain microbial communities consisting of Fusobacteria, Proteobacteria, Bacteroidetes, and Firmicutes, with variations based on tissue type along the length of the digestive tract. The overall dominance of Fusobacteria is distinct from any other …

Cyclic Distributional Model Of The Late Moscovian Fusulinids In The Donets Basin (Ukraine) In Response To Eustatic Sea Level Fluctuations And Its Application In Biostratigraphy And Correlation, Rimma Khodjanyazova

Boise State University Theses and Dissertations

The continuous Pennsylvanian shallow-marine, paralic, siliciclastic succession in the Donets Basin is pivotal for correlation of marine and continental strata in northern Pangaea with coeval shallow-marine mainly carbonate strata in the Moscow Basin, a historical type area of Moscovian Horizons. The details of the history of establishment, lithostratigraphy and current biostratigraphy of Podolskian and Myachkovian Horizons in the Moscow Basin that are not readily available in Western literature are reviewed.

A model of cyclic recurrence (~0.6 —1myr) of three main fusulinid assemblages in the Pennsylvanian siliciclastic-carbonate succession in the Donets Basin is proposed. A Hemifusulina-association (A) indicates the onset …

Early Permian Seawater From The Delta18o Record Of Fossil Bivalves: Seasonality And A Latitudinal Gradient, James Andrew Beard

Earth & Environmental Sciences - Theses

The transition from a glaciated world to one that was ice-free makes the early Permian a time interval that in many ways mirrors the present, and hence there is great interest in constraining paleoclimate conditions over that transition. A common method for estimating ancient temperatures uses the oxygen isotope composition of marine carbonate, but this approach becomes significantly more complicated prior to the Cretaceous due to uncertainties about diagenesis and the isotopic composition of seawater, which has been hypothesized to be more depleted than during the Cenozoic. I use stable isotope compositions of sequentially microsampled accretionary calcite from fossil bivalves …