Physical Sciences and Mathematics Commons^™

Life On The Edge: The Cambrian Marine Realm And Oxygenation, Sara Pruss, Benjamin C. Gill

Geosciences: Faculty Publications

The beginning of the Phanerozoic saw two biological events that set the stage for all life that was to come: (a) the Cambrian Explosion (the appearance of most marine invertebrate phyla) and (b) the Great Ordovician Biodiversification Event (GOBE), the subsequent substantial accumulation of marine biodiversity. Here, we examine the current state of understanding of marine environments and ecosystems from the late Ediacaran through the Early Ordovician, which spans this biologically important interval. Through a compilation and review of the existing geochemical, mineralogical, sedimentological, and fossil records, we argue that this interval was one of sustained low and variable marine …

After Awhile...Crocodile?: An Assessment Of Crocodylians As Living Fossils, Caleb N. Lepore

Proceedings of the International Conference on Creationism

Crocodylians, which include extant crocodiles, alligators, caimans, the gharial, and the tomistoma, are often considered living fossils. Many evolutionists have argued that the term ‘living fossil’ is inappropriately applied to crocodylians, since past diversity within Crocodylia, as well as within the more inclusive group Crocodylomorpha, implies that they have evolved substantially since their first appearance in the fossil record. In contrast, many creationists argue that the morphological conservativeness of living fossils like crocodylians is unexpected from a gradualistic model of evolution. To clarify this issue, we argue that while the term ‘living fossil’ has varied meanings within the literature, morphological …

A Multidisciplinary Approach To Resolving The End-Guadalupian Extinction, Christopher R. Fielding, Scott E. Bryan, James L. Crowley, Tracy D. Frank, Michael T. Hren, Chris Mays, Stephen Mcloughlin, Jun Shen, Peter J. Wagner, Arne Winguth, Cornelia Winguth

Geosciences Faculty Publications and Presentations

The transition from the middle to late Permian (Guadalupian–Lopingian) is claimed to record one or more extinction events that rival the ‘Big Five’ in terms of depletion of biological diversity and reorganization of ecosystem structure. Yet many questions remain as to whether the events recorded in separate regions were synchronous, causally related, or were of a magnitude rivaling other major crises in Earth's history. In this paper, we survey some major unresolved issues related to the Guadalupian–Lopingian transition and offer a multidisciplinary approach to advance understanding of this under-appreciated biotic crisis by utilizing records in Southern Hemisphere high-palaeolatitude settings. We …

The Influence Of Local Immigration And Extinction Of Species On Spatial Heterogeneity Of Vegetation In Semi-Natural Grasslands In Japan, Taisuke Yasuda, Masae Shiyomi, T. Egawa, K. Sei, R. Ishikawa, S. Takahashi

IGC Proceedings (1997-2023)

Spatiotemporal variation in the local immigration and extinction of species in a community may form and change the spatial heterogeneity (SH) of vegetation but few studies have evaluated the influences of these processes on SH. SH often occurs in grassland grazed by cattle and sheep. Understanding the formation and dynamics of SH is important because SH profoundly affects local and regional ecological processes. We propose a new way to quantify the effect of the local immigration and extinction of species on SH, and try to clarify the influence of the processes on SH

Land Use History And The Build-Up And Decline Of Species Richness In Scandinavian Semi-Natural Grasslands, O. Eriksson, S. A. O. Cousins, R. Lindborg

IGC Proceedings (1997-2023)

Scandinavian semi-natural grasslands have an exceptionally high small-scale species richness. In the past, these grasslands covered extensive areas but they have declined drastically during the last century. How species richness of semi-natural grasslands was built up during history, and how species respond to land use change, are discussed. The agricultural expansion from the late Iron Age was associated with increasing grassland extent and spatial predictability, resulting in accumulation of species at small spatial scales. Although few species directly depend on management, the specific composition of these grasslands is a product of haymaking and grazing. Grassland fragmentation initially has small effects …

The Mystery Of The Missing Megafauna, Maggie Colangelo, Bernard Means

Virtual Curation Lab's Comic Publications

The creative team behind Founding Monsters and Founding Monsters Tales have created a new comic that takes a more scientific and less historic approach to the giant mammals that once roamed North America. The Mystery of the Missing Megafauna explores how changing climate impacted biodiversity and megafauna populations in North America at the end of the last Ice Age. Particular attention is placed on the extinction of mastodons, mammoths, giant ground sloths and other megafauna whose fossils are found at Saltville in southwestern Virginia. This comic draws a connection to contemporary climate change and the major extinctions happening today. The …

A Miocene Nannofossil Biostratigraphic Case Study: Alaminos Canyon Block 627 And Mississippi Canyon Block 555, And Sedimentation Rates In The Gulf Of Mexico, Bethany L. Cobb Faulk, Murlene W. Clark

Gulf and Caribbean Research

The Miocene sediments of 2 deep—water boreholes from the northern Gulf of Mexico, from Alaminos Canyon (AC) Block 627 and Mississippi Canyon (MC) Block 555, have been biostratigraphically analyzed using calcareous nannofossils, revealing changes in sedimentation rates and depositional environments between these 2 areas. High nannofossil abundance values and low sedimentation rates generally recorded in the Alaminos Canyon region suggest a condensed section during much of the Miocene, associated with a basinal environment. Mississippi Canyon exhibits lower nannofossil abundance and higher sedimentation rates compared to Alaminos Canyon during the majority of the Miocene. Increased sediment volumes are largely attributed to …

The Role Of Carbonate Factories And Sea Water Chemistry On Basin-Wide Ramp To High-Relief Carbonate Platform Evolution: Triassic, Nanpanjiang Basin, South China, Daniel J. Lehrmann, Leanne M. Stepchinski, Hannah E. Wolf, Liangzi Li, Xiaowei Li, Marcello Minzoni, Meiyi Yu, Jonathan L. Payne

Geosciences Faculty Research

The end-Permian extinction and its aftermath altered carbonate factories globally for millions of years, but its impact on platform geometries remains poorly understood. Here, the evolution in architecture and composition of two exceptionally exposed platforms in the Nanpanjiang Basin are constrained and compared with geochemical proxies to evaluate controls on platform geometries. Geochemical proxies indicate elevated siliciclastic and nutrient fluxes in the basal Triassic, at the Induan—Olenekian boundary and in the uppermost Olenekian. Cerium/Ce* shifts from high Ce/Ce* values and a lack of Ce anomaly indicating anoxia during the Lower Triassic to a negative Ce anomaly indicating oxygenation in the …

End-Permian (252 Mya) Deforestation, Wildfires And Flooding—An Ancient Biotic Crisis With Lessons For The Present, Vivi Vajda, Stephen Mcloughlin, Chris Mays, Tracy D. Frank, Christopher R. Fielding, Allen Tevyaw, Veiko Lehsten, Malcolm Bocking, Robert S. Nicoll

Department of Earth and Atmospheric Sciences: Faculty Publications

Current large-scale deforestation poses a threat to ecosystems globally, and imposes substantial and prolonged changes on the hydrological and carbon cycles. The tropical forests of the Amazon and Indonesia are currently undergoing deforestation with catastrophic ecological consequences but widespread deforestation events have occurred several times in Earth’s history and these provide lessons for the future. The end-Permian mass-extinction event (EPE; ∼252 Ma) provides a global, deep-time analogue for modern deforestation and diversity loss. We undertook centimeter-resolution palynological, sedimentological, carbon stable-isotope and paleobotanical investigations of strata spanning the end- Permian event at the Frazer Beach and Snapper Point localities, in the …

Using Stable Isotopes To Understand Survival Versus Extinction Of Late Pleistocene Muskoxen, Stephanie Mabee

Electronic Thesis and Dissertation Repository

This thesis uses stable isotopes to investigate the adaptive advantages of Ovibos moschatus, a muskox, relative to now-extinct Pleistocene megafauna in eastern Beringia (Yukon Territory and Alaska), including another muskox Bootherium bombifrons. Ecological niches were defined for Ovibos and Bootherium using stable carbon and nitrogen isotope compositions of bone collagen. Plant remains trapped in modern Ovibos molars were used to determine the carbon and nitrogen isotope collagen-diet discrimination factors, which were then applied to ancient specimens. Ovibos possessed larger isotopic – and hence ecological – niches than Bootherium across eastern Beringian sites. The larger niche suggests that Ovibos …

Mercury Chemostratigraphy Across The Cambrian Series 2 – Series 3 Boundary: Evidence For Increased Volcanic Activity Coincident With Extinction?, L. E. Faggetter, P. B. Wignall, S. B. Pruss, D. S. Jones, S. Grasby, M. Widdowson, R. J. Newton

Geosciences: Faculty Publications

Flood basalt volcanism represented by the Kalkarindji Province (Australia) is temporally associated with a trilobite mass extinction at the Cambrian Series 2 – Series 3 boundary, providing one of the oldest potential links between volcanism and biotic crisis in the Phanerozoic. However, the relative timing of flood basalt volcanism (Kalkarindji Province, Australia) and the trilobite extinctions, first recorded in North America, is not known. Mercury (Hg) enrichment in the sedimentary record provides a potential proxy for volcanism which may facilitate improved chronologies of eruption and extinction. Here we report mercury records for three sections from mid-shelf strata of the Great …

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

Graduate Theses, Dissertations, and Problem Reports

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 …

Devonian Stromatoporoid Interactions At The Falls Of The Ohio State Park, Clarksville, Indiana, Morgan Sierra Hall

Undergraduate Theses

Stromatoporoids are calcitic sponges that occurred in the fossil record from the Early Ordovician to Late Devonian period. These sponges interacted with other organisms, especially rugose and tabulate corals. Some corals appear to benefit from the rigidity of stromatoporoids in response to turbulent waters. Stromatoporoids and many corals went extinct during the Frasnian-Famennian crisis when paleoenvironmental parameters were shifting. Studying the relationships between these taxa may provide insight to their vulnerability during the extinction.

This research was performed at the Falls of the Ohio in Clarksville, Indiana. Organisms in the Coral Zone were studied using transect sampling. Each fossil along …

Conflicting Theories: Impact And Volcanism, Dimitrik Johnson

Student Writing

The K-Pg extinction (or K-T extinction), more commonly referred to as the extinction of the dinosaurs, is the most recent mass extinction event in Earth’s history. The causes of the event have been widely debated, with the two main theories being a large asteroid impact or volcanism. While some scientists disagree, the most popular and agreed upon theory is that a large asteroid impacted Earth 65 million years ago, creating a toxic dust cloud that filled the atmosphere, and resulted in the eventual extinction of most of the dinosaurs. This theory was first brought to life by Luis Alvarez, his …

Review Of The Ends Of The World: Volcanic Apocalypses, Lethal Oceans, And Our Quest To Understand Earth's Past Mass Extinctions, By Peter Brannen, Robert F. Diffendal Jr.

Robert F. Diffendal, Jr., Publications

In his new best-selling book, Peter Brannen, award-winning science writer, takes you on a fascinating trip through the run-up to the end of the Cretaceous extinction event and the K-Pg (Cretaceous/Paleogene) boundary, formerly called the K-T (Cretaceous/Tertiary) boundary.

Brannen interviewed many scientists who studied these events and went on field trips with them to major Cretaceous sites and to those where earlier and later extinction events happened. He presents clear explanations of what is known and not known about all of these events in a largely error-free book. Brannen details the other four big extinction events in geologic history: the …

Lilliput Effect Dynamics Across The Cretaceous-Paleogene Mass Extinction: Approaches, Prevalence, And Mechanisms, Matthew Brett Jarrett

USF Tampa Graduate Theses and Dissertations

An organism's body size entails both physiological and ecological costs. Furthermore, as a parameter in analyzing organisms, it represents a fundamental and essential morphometric character. Reductions in size following mass extinction is a commonly observed phenomenon in the fossil record. This study examines the evolutionary significance of this phenomenon termed the: 'Lilliput Effect' by proposing that it represents a rapid evolutionary response to altered selection pressures during a mass extinction. This primary hypothesis is evaluated against two additional hypotheses of size reduction: 1) stunted growth as a response to stressed ecosystems, and/or 2) mass extinctions are size selective.

These hypotheses …

Extinction Intensity, Selectivity And Their Combined Macroevolutionary Influence In The Fossil Record, Jonathan L. Payne, Andrew M. Bush, Ellen T. Chang, Noel A. Heim, Matthew L. Knope, Sara B. Pruss

Geosciences: Faculty Publications

The macroevolutionary effects of extinction derive from both intensity of taxonomic losses and selectivity of losses with respect to ecology, physiology and/or higher taxonomy. Increasingly, palaeontologists are using logistic regression to quantify extinction selectivity because the selectivity metric is independent of extinction intensity and multiple predictor variables can be assessed simultaneously. We illustrate the use of logistic regression with an analysis of physiological buffering capacity and extinction risk in the Phanerozoic marine fossil record. We propose the geometric mean of extinction intensity and selectivity as a metric for the influence of extinction events. The end-Permian mass extinction had the largest …

Did Shell-Crushing Crabs Trigger An Escalatory Arms Race In The Aftermath Of A Late Neogene Regional Mass Extinction Event? An Experimental Test, Lisa B. Whitenack, Gregory S. Herbert

School of Geosciences Faculty and Staff Publications

A regional mass extinction event in the late Neogene western Atlantic is widely thought to have generated evolutionary opportunities for survivors, including enemy-related adaptation (escalation). The Strombus alatus species complex is one potential example of this phenomenon. Strombid gastropods are abundant in the Plio-Pleistocene fossil record and Recent in subtropical Florida, and the percentage of these shells bearing a row of short spines on the last whorl increased from nearly zero to almost 100% over this time. As shell ornamentation is one of the most frequently cited defenses against both peeling and crushing predators, we exposed live spined and spineless …

Ice-Age Megafauna In Arctic Alaska: Extinction, Invasion, Survival, Daniel H. Mann, Pamela Groves, Michael L. Kunz, Richard E. Reanier, Benjamin V. Gaglioti

United States Geological Survey: Staff Publications

Radical restructuring of the terrestrial, large mammal fauna living in arctic Alaska occurred between 14,000 and 10,000 years ago at the end of the last ice age. Steppe bison, horse, and woolly mammoth became extinct, moose and humans invaded, while muskox and caribou persisted. The ice age mega fauna was more diverse in species and possibly contained 6x more individual animals than live in the region today. Mega faunal biomass during the last ice age may have been 30x greater than present. Horse was the dominant species in terms of number of individuals. Lions, short-faced bears, wolves, and possibly grizzly …

Using Marine Snails To Teach Biogeography And Macroevolution: The Role Of Larvae And Dispersal Ability In The Evolution And Persistence Of Species, Jonathan R. Hendricks

Faculty Publications

While some marine animals are capable of traveling great distances, many have limited mobility as adults and spend the majority of their lifetimes in a small geographical area or may even be cemented to a single place. While it might be expected that species with limited mobility would have small geographic distributions, some nevertheless occur over very large areas. This is the case for some marine snails (gastropods). A key factor that impacts the geographic distribution of marine snails is the type of larvae they have during the phase of their life history that follows hatching from an egg. Because …

Using Marine Snails To Teach Biogeography And Macroevolution: The Role Of Larvae And Dispersal Ability In The Evolution And Persistence Of Species, Jonathan R. Hendricks

Jonathan R. Hendricks

While some marine animals are capable of traveling great distances, many have limited mobility as adults and spend the majority of their lifetimes in a small geographical area or may even be cemented to a single place. While it might be expected that species with limited mobility would have small geographic distributions, some nevertheless occur over very large areas. This is the case for some marine snails (gastropods). A key factor that impacts the geographic distribution of marine snails is the type of larvae they have during the phase of their life history that follows hatching from an egg. Because …

Late Quaternary Distribution And Biogeography Of The Southern Lake Eyre Basin (Sleb) Megafauna, South Australia, Steve Webb

Steve Webb

Understanding the population demography, species distribution and biogeography of Australia’s megafauna is essential for understanding their extinction. This process is only just beginning, and this article discusses these aspects while concentrating on a particular region; the southern Lake Eyre Basin (SLEB). It is also the first detailed description of the distribution of megafauna across that region of central Australia. The data are based on an extensive longitudinal study of 41 palaeontological sites spread across 250 000km2. Megafauna adaptation and response to extensive environmental change during the late Quaternary is reflected in the composition and distribution of 21 megafauna species found …

Late Quaternary Distribution And Biogeography Of The Southern Lake Eyre Basin (Sleb) Megafauna, South Australia, Steve Webb

Steve Webb

Understanding the population demography, species distribution and biogeography of Australia’s megafauna is essential for understanding their extinction. This process is only just beginning, and this article discusses these aspects while concentrating on a particular region; the southern Lake Eyre Basin (SLEB). It is also the first detailed description of the distribution of megafauna across that region of central Australia. The data are based on an extensive longitudinal study of 41 palaeontological sites spread across 250 000km2. Megafauna adaptation and response to extensive environmental change during the late Quaternary is reflected in the composition and distribution of 21 megafauna species found …

Responses Of Pond-Breeding Amphibians To Wildfire: Short-Term Patterns In Occupancy And Colonization, Blake R. Hossack, Paul Stephen Corn

United States Geological Survey: Staff Publications

Wildland fires are expected to become more frequent and severe in many ecosystems, potentially posing a threat to many sensitive species. We evaluated the effects of a large, stand-replacement wildfire on three species of pond-breeding amphibians by estimating changes in occupancy of breeding sites during the three years before and after the fire burned 42 of 83 previously surveyed wetlands. Annual occupancy and colonization for each species was estimated using recently developed models that incorporate detection probabilities to provide unbiased parameter estimates. We did not find negative effects of the fire on the occupancy or colonization rates of the long-toed …

Biogeography Of The Late Paleocene Benthic Foraminiferal Extinction, Ellen Thomas

Ellen Thomas

During the Late Paleocene Thermal Maximum (LPTM) benthic foraminifera at middle bathyal and greater depths suffered extinction of 30-50% of species during a few thousand years. Extinction was less severe at neritic to upper bathyal depths, where temporary changes in faunal composition prevailed. Pre-extinction deep-sea faunas were cosmopolitan and diverse, and contained heavily calcified species. Immediate post-extinction faunas were more variable geographically, exhibited low diversity, and were dominated by thin-walled calcareous or agglutinated taxa, possibly because CaCO3 dissolution increased globally from neritic to abyssal depths just before the extinction. These assemblages were dominated either by long-lived taxa such as Nuttallides …