Paleobiology Commons^™

Middle Miocene Paleoenvironmental Reconstruction Of The Central Great Plains From Stable Carbon Isotopes In Large Mammals, Willow H. Nguy

Dissertations & Theses in Earth and Atmospheric Sciences

Middle Miocene (18-12 Mya) mammalian faunas of the North American Great Plains contained a much higher diversity of apparent browsers than any modern biome. This has been attributed to greater primary productivity, which may have supported greater browser diversity that commonly corresponds with densely vegetated habitats. However, several lines of proxy evidence suggest that open woodlands or savannas dominated middle Miocene biomes; neither of which support many browsers today. Stable carbon isotopes in mammalian herbivore tooth enamel were used to reconstruct vegetation structure of middle Miocene biomes.

Stable carbon isotopes in C₃ dominated environments reflect vegetation density and herbivores ...

Exploring The Calvert Cliffs: Interpreting Classic Miocene Sequences Through The Application Of Strontium Isotope Stratigraphy And Paleoecology, Joshua B. Zimmt

Undergraduate Honors Theses

The Calvert Cliffs (Maryland, USA) is a classic condensed Miocene sequence that has attracted much scientific attention for its laterally extensive and highly condensed fossil beds (Kidwell, 1982a). Several meters thick and up to 70% shell material, the period of formation of these major complex shell beds has been debated for decades. Kidwell (1989) and associated studies have demonstrated that the major complex shell beds possess certain characteristics that suggest the beds formed as a succession of condensed parasequences during a transgressive systems tract. However, no quantitative analysis has calculated the period of formation of the major complex shell beds ...

The Homology And Phylogeny Of The Diploporita (Blastozoa: Echinodermata), Sarah Lynne Sheffield

Doctoral Dissertations

Evolutionary relationships of extinct echinoderms are poorly understood, especially within stem-bearing blastozoans, a large group of echinoderms with unique respiratory structures and feeding brachioles. They were highly experimental in their body plans and very unlike echinoderms today (e.g., sea urchins). Many of the blastozoan subgroups recognized in recent classifications do not represent clades (natural associations of organisms derived from a single ancestor); they are either grades of organization or groups united by superficially similar features. Consequently, these ‘traditional’ groupings cannot be used to analyze evolutionary questions, such as biogeography or rates of evolution. This problem is highlighted within the ...

Understanding Feathered Dinosaurs, Michael D. Sprague

The Research and Scholarship Symposium

Young-earth creationists hold to separate creations of birds and land animals due to a literal interpretation of Genesis 1:20-25, which describes their creations on different days. As such, they oppose the conventional model of theropod-to-bird evolution. For many years, there were few Mesozoic birds known, namely Hesperornis and Icthyornis. Specimens such as Archaeopteryx, found in 1861, seemed to strengthen the argument for the proposed transition. However, even after John Ostrom reinvigorated the idea of dinosaur-to-bird evolution in 1960 with the discovery of Deinonychus, evidence of this transition was still sparse. In the 1990’s, exquisitely-preserved dinosaur fossils began to ...

Understanding Feathered Dinosaurs, Michael D. Sprague

The Research and Scholarship Symposium

Young-earth creationists hold to separate creations of birds and land animals due to a literal interpretation of Genesis 1:20-25, which describes their creations on different days. As such, they oppose the conventional model of theropod-to-bird evolution. For many years, there were few Mesozoic birds known, namely Hesperornis and Icthyornis. Specimens such as Archaeopteryx, found in 1861, seemed to strengthen the argument for the proposed transition. However, even after John Ostrom reinvigorated the idea of dinosaur-to-bird evolution in 1960 with the discovery of Deinonychus, evidence of this transition was still sparse. In the 1990’s, exquisitely-preserved dinosaur fossils began to ...

An Investigation Of Paleo-Wildfires During The Cretaceous-Paleogene (K-Pg) Boundary At El Kef, Tunisia, Michael Gross

Undergraduate Honors Theses

The causes and consequences of the Cretaceous-Paleogene mass extinction have long been a source of contention. Several models predict that enough thermal radiation from the bolide impact was produced to ignite wildfires at least regionally and possibly on a global scale, raising average temperatures by up to ~10°C, and releasing large amounts of CO₂ and CO. However, the role of regional versus global wildfire events as an environmental stressor, as well as the sources of the fire (land vegetation vs. hydrocarbon reservoirs) and its expression in terrestrial and marine archives, remains controversial. Typically, wildfires are preserved in the ...

Locomotion And Skeletal Morphology Of Late Cretaceous Mosasaur, Tylosaurus Proriger, Jesse A. Carpenter

University Honors Program Theses

Mosasaurs (Reptilia: Squamata) are apex marine predators from the Late Cretaceous (Turonian to Maastrichtian) epicontinental seas of North America, Africa, Europe, and Asia. From previous studies, it has been suggested that this group trends towards increased rib compactness, lengthening and increased posterior inclination of neural spines of intermediate and terminal caudal vertebrae to support a caudal fluke, and a transition from anguilliform to carangiform locomotion, closer to thunniform in pelagic adapted species. This study examined multiple Tylosaurus specimens using centrum length/width (CL/CW) and width/height (CW/CH) ratios along with neural spine height and angle of posterior inclination ...

G:, Taylor Lafe Cantrall

Senior Projects Spring 2017

Senior Project submitted to The Division of Languages and Literature of Bard College.

Lessons From The Past: Unfolding The Dynamics Among Climate, Balkan Landscapes, And Humans Over The Past Millennium, Charuta J. Kulkarni

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

The primary objective of this doctoral dissertation is to reconstruct the environmental history of the Central Balkans (Serbia) over the past millennium utilizing biological proxies (pollen, spores, and charcoal), geochemical signals through X-ray fluorescence (XRF), statistical analyses, and atomic mass spectrometry (AMS) ¹⁴C chronology. This dissertation establishes the first chronological framework for vegetation-landscape changes in Serbia and discusses the role of humans and climate as underlying processes.

Chapter 1 discusses the background and the nature of the research problem followed by the extensive literature review on the topic of the Holocene climate and paleoecology. The state of Holocene paleoecology ...

First Major Appearance Of Brachiopod-Dominated Benthic Shelly Communities In The Reef Ecosystem During The Early Silurian, Cale A.C. Gushulak

Electronic Thesis and Dissertation Repository

The early Silurian reefs of the Attawapiskat Formation in the Hudson Bay Basin preserved the oldest record of major invasion of the coral-stromatoporoid skeletal reefs by brachiopods and other marine shelly benthos, providing an excellent opportunity for studying the early evolution, functional morphology, and community organization of the rich and diverse reef-dwelling brachiopods. Biometric and multivariate analysis demonstrate that the reef-dwelling Pentameroides septentrionalis evolved from the level-bottom-dwelling Pentameroides subrectus to develop a larger and more globular shell. The reef-dwelling brachiopods in the paleoequatorial Hudson Bay Basin were more diverse than contemporaneous higher latitude reef-dwelling brachiopod faunas, with ten distinct community ...

Testing The Temporal Stability Of The Climate Response Of Tree Species At Norris Dam State Park, Tennessee, U.S.A., Allison Elizabeth Ingram

Masters Theses

Temporal stability of the climate-tree growth relationship means that over time, tree species were responding to a specific climate variable and continue to respond to that variable into the present. The stability of this response is important to test prior to attempting to reconstruct past climate. In this study, I sampled oaks (white oak = Quercus alba L. and chestnut oak = Quercus montana Willd.) and pines (Virginia pine = Pinus virginiana Mill. and shortleaf pine = Pinus echinata Mill.) growing in Norris Dam State Park in eastern Tennessee and tested the temporal stability of these species and their potential for reconstructing past climate ...

Santonian—Campanian Calcareous Nannofossil Paleobiogeography, Brandi R. Moore

Dissertations & Theses in Earth and Atmospheric Sciences

Calcareous nannofossil abundance data from 11 DSDP/ODP sites were analyzed by multivariate methods to assess the paleoceanographic change that is associated with the Santonian-Campanian boundary transition. Data were divided into Santonian or Campanian age groups based on the presence or absence of the lower Campanian nannofossil species, Aspidolithus parcus parcus. All assemblages are dominated by Watznaueria barnesiae, Micula decussata, and Prediscosphaera intercisa. Analyses determined that the relative abundance of M. decussata generally reflects a change in temperature, with a preference for cool water. Prediscosphaera intercisa appears to have had an inverse abundance relationship with M. decussata, suggesting that P ...

Reconstructing The Paleoecology And Biogeography Of Rhinoceroses (Mammalia: Rhinocerotidae) In The Great Plains Of North America, Leading Up To Their Extinction In The Early Pliocene, Bian Wang

Dissertations & Theses in Earth and Atmospheric Sciences

Members of the family Rhinocerotidae first appeared in the middle Eocene and were one of most successful mammal groups of the Oligocene and Miocene in North America. Their extinction in the early Pliocene has been attributed to several causes, including cooling climate, an expansion of C₄ grasslands, and faunal turnover favoring high-crowned, open habitat-adapted mammalian taxa. This study tests whether the extinction of North American rhinoceroses in the Great Plains was abrupt or gradual by examining changes in their paleogeographic distribution in a series of time-slices through the Barstovian, Clarendonian, and Hemphillian North American land-mammal ages. It further examines ...

Shell Bluff – A Fossiliferous Ridge, The Site Of The Extinct Oyster Crassostrea Gigantissima And History Of Its Identification, Elliott O. Edwards Jr.

Georgia Journal of Science

Shell Bluff is described by geologists as stratigraphically one of the most important exposures in the Georgia Coastal Plain because the bluff is home to the large oyster, Crassostrea gigantissima, now extinct. Native Americans inhabited this area prior to Hernando DeSoto and his men who visited the area in 1540. They were probably the first Europeans to visit Shell Bluff. John and son William Bartram visited the bluff in 1764 and John described the bluff in his journal and the existence of large oysters. The British naturalist, John Finch, described a fossil oyster taken from the site in 1824 as ...

Cone In Cone Concretions Of The Stanley Group In Southeastern Oklahoma, Kyle B. Ayres

Electronic Theses and Dissertations

Cone in cone concretions found in the Stanley Group of Southeastern Oklahoma have a variety of external and internal attributes which allow diagenetic and theoretical models of formation to be hypothesized. Stanley Group carbonate cone in cone concretions are initially formed in sulfur reducing horizons at shallow burial depths in a poorly circulated possibly deep trough containing siliceous sediments and organic matter. Collected concretions near the town of Smithville, Oklahoma displayed four different external morphologies and four variations of mineral constituents. All concretions contained microscopic cones which initiated diffusion and/or fluid patterns and is an early cementation process that ...

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 ...

The End-Permian Mass Extinction And The Siberian Traps Eruptions, Rebecca Teed

Earth and Environmental Sciences Faculty Publications

This handout focuses on the evidence for the theory that a series of flood-basalt eruptions in Siberia caused the mass extinction at the end of the Permian Period. This is the worst mass extinction known to geologists, and 90% or more of all species on Earth were wiped out. It is part of a set of four articles on possible causes of the Permian and Cretaceous mass extinctions that can be used to organize classroom debates or to have students compare and contrast the events and their causes.

The End-Cretaceous Mass Extinction And The Deccan Traps Eruptions, Rebecca Teed

Earth and Environmental Sciences Faculty Publications

This handout focuses on the evidence for the theory that a series of flood-basalt eruptions in northern India caused the mass extinction at the end of the Cretaceous Period. The dinosaurs and about 75% of all marine invertebrate species and many other organisms died abruptly at this time. This is one of a set of four articles on possible causes of the Permian and Cretaceous mass extinctions that can be used to organize classroom debates or to have students compare and contrast the events and their causes.

The End-Cretaceous Mass Extinction And The Chicxulub Impact, Rebecca Teed

Earth and Environmental Sciences Faculty Publications

This handout focuses on the evidence for the theory that a massive meteor impact off the coast of Mexico caused the mass extinction at the end of the Cretaceous Period. The dinosaurs and about 75% of all marine invertebrate species and many other organisms died abruptly at this time. It is part of a set of four articles on possible causes of the Permian and Cretaceous mass extinctions that can be used to organize classroom debates or to have students compare and contrast the events and their causes.

The End-Permian Mass Extinction And A Possible Massive Impact, Rebecca Teed

Earth and Environmental Sciences Faculty Publications

This handout examines the evidence for the theory that a massive meteor impact caused the mass extinction at the end of the Permian Period. This is the worst mass extinction known to geologists, and 90% or more of all species on Earth were wiped out. It is part of a set of four articles on possible causes of the Permian and Cretaceous mass extinctions that can be used to organize classroom debates or to have students compare and contrast the events and their causes.