Master of Science, The Ohio State University, 2007, Graduate School

Committee: Not Provided (Other) Subjects:

PHD, Kent State University, 2022, College of Arts and Sciences / Department of Earth Sciences

This dissertation contains 6 chapters which examine the effects of volcanic ash deposition on paleoenvironment, sedimentology, fossil preservation, and paleoecology. It includes field-based research and experimental data which demonstrate that volcanic ash deposition can play an important role in shaping the nature of the sedimentary and fossil records in marine settings at both distal and proximal localities. Chapters 1 and 2- Summary and introduction. Chapter 3 – This chapter discusses two Cenozoic marginal marine settings which occur proximal (within 100 km) to prominent volcanic centers; one in the Pacific Northwestern United States, and one in the south of the Patagonian Cordillera, Argentina. The Oligocene Lincoln Creek Formation in Washington contains an exceptionally well-preserved marine fauna dominated by crustaceans and mollusks, and the late Miocene-early Oligocene Estancia 25 de Mayo Formation in southern Patagonia, Argentina, contains a similar exceptionally preserved fauna. In both settings, evidence shows that exceptional fossil preservation was facilitated by the deposition of mass quantities of volcanic ash via marine hyperpycnal flows following large volcanic eruptions. Chapter 4 – As discussed in the previous chapter, volcanic sediments can facilitate exceptional fossil preservation. The rapid deposition of fine-grained material in marine settings can preserve fossil material which may otherwise not be preserved. One such example of preservation in volcanic ash is a new species of isopod from the above-described Estancia 25 de Mayo Formation. In this chapter, Cirolana centinelensis n. sp. is described as the first known occurrence of the Isopoda in the fossil record of Argentina. The chapter discusses the recalcitrance of fossil isopods with respect to preservation and elucidates how the rapid deposition of volcanic ash facilitated the preservation of this exceptionally rare fossil specimen. Also discussed are the vagaries of the f (open full item for complete abstract)

Committee: Rodney Feldmann (Advisor); Carrie Schweitzer (Committee Co-Chair); Silvio Casadio (Committee Member); Joseph Ortiz (Committee Member) Subjects: Geology; Paleoecology; Paleontology

PHD, Kent State University, 2022, College of Arts and Sciences / Department of Earth Sciences

This dissertation includes seven written chapters that each identify some uses for fossil and recent marine arthropod cuticle across studies pertaining to paleoecology, taphonomy, morphometrics, and systematic or evolutionary analyses. Chapters 1 and 2 are the dissertation Summary and Introduction, respectively. Chapter 3 describes a paleoecological study that pertained to how other organisms have interacted with arthropod cuticle. Chapter 3 focuses on the potential for modern paddle-bearing and non-paddle-bearing brachyuran crabs to remove infesting epibionts via grooming the surface cuticle of their carapaces. The modern crabs were used as proxies for several analogous fossil specimens from middle Cenozoic rocks from Oregon and Washington State to help differentiate in-vivo and post-mortem cuticle infestation by epibionts. Chapter 4 was a morphometrics study pertaining to population dynamics of the Pennsylvanian horseshoe crab Euproops danae from a new locality near Windber, Pennsylvania. By analyzing changes in surface cuticle morphology across ontogenetic stages, we can determine which cuticle characters are morphologically stable and which characters are more common across juvenile and adult members of a population. Chapter 5 describes several actualistic taphonomic experiments that were conducted to document how horseshoe crab corpse and molt cuticle break down over time when agitated in various sediment types and sizes. These experiments were performed to simulate conditions that may have led to the broken and disarticulated horseshoe crab fossil carapaces preserved in Late Jurassic lithographic limestones from Owadow-Brzezinki, Poland, to better-understand biostratinomic processes associated with horseshoe crab cuticle preservation. Chapter 6 considered the potential for marine arthropod cuticle microstructure characters to be implemented in systematic or evolutionary studies. It was the first study to create codeable cross-sectional and surfi (open full item for complete abstract)

Committee: Rodney Feldmann (Committee Chair); Loren Babcock (Committee Member); Joseph Ortiz (Committee Member); Carrie Schweitzer (Committee Co-Chair) Subjects: Geobiology; Geology; Morphology; Paleoecology; Paleontology

Master of Science, The Ohio State University, 2021, Earth Sciences

Most of the fossil record consists of "ordinary" deposits, those where only biomineralized parts such as teeth, shells, and bones are preserved. Rarely, when the proper conditions are met, nonbiomineralized tissues such as guts and muscles also can be preserved. These deposits can reveal new insights into the biology, ecology, and taphonomy of ancient organisms, so identifying and understanding them is critical to paleontology. Anoxia is one of the conditions thought to be necessary for exceptional preservation. Because of this, "ordinary" deposits from predominantly aerobic depositional settings have been largely disregarded as potential sites for exceptional preservation. The discovery of pyritized nonbiomineralized tissues in the Silica Shale (Devonian) of Ohio, Michigan, and Indiana seems to contradict historical assumptions about environments conducive to exceptional preservation. This study characterizes the extent of exceptional preservation in the Silica Shale, and provides a comparison with another similar "ordinary" deposit for exceptional preservation, the Cincinnatian (or 'Cincinnati Group'; Ordovician) of Ohio, Kentucky, and Indiana. Comparing these two occurrences provides insight into the mechanism for exceptional preservation in these deposits. Fossil specimens were examined using X-ray Computed Tomography (XCT) to non-destructively view internal structures. In total, 247 specimens from the Silica Shale and 102 specimens from the Cincinnatian were examined. They represent a variety of taxa including brachiopods, trilobites, corals, cephalopods, gastropods, bivalves, and echinoderms. More than 60% of Silica Shale specimens and 20% of Cincinnatian specimens contained pyritized nonbiomineralized tissues. XCT analysis reveals that one brachiopod specimen from the Silica Shale, assigned to Paraspirifer bownockeri, lived with situs ambiguous. In both the Silica Shale and the Cincinnatian, rapid burial during storm events likely created local, tempora (open full item for complete abstract)

Committee: Loren Babcock (Advisor); Jill Leonard-Pingel (Committee Member); Ann Cook (Committee Member) Subjects: Earth; Geology; Paleoecology; Paleontology

MS, Kent State University, 2020, College of Arts and Sciences / Department of Earth Sciences

Experiments using artificial sea water, sediment, and varying combinations thereof to represent different environmental settings yielded different decay rates of penaeid shrimp. Experiments were monitored by scoring decay-induced morphologies, including those commonly observed in compressed shrimp fossils. Changes in microstructural layering of cuticle and pH were also monitored throughout decay. Burial of the shrimp in kaolinite mud (powder saturated with artificial sea water) inhibited decay while the fastest decay occurred with shrimp lying unburied on the sediment-water interface. A small percentage of lime (10%) with kaolinite also resulted in slightly decreased decay rates in shrimp that experienced minor sedimentation within artificial sea water. Procedural and methodological concerns were identified from this series of sediment-based experiments. Experimental protocols and considerations for future decay experiments are suggested along with potential experimental conditions, the results of which could further taphonomic interpretations of taxonomically characteristic morphologies preserved in shrimp or other commonly compressed fossils.

Committee: Carrie Schweitzer Ph.D. (Advisor); Rodney Feldmann Ph.D. (Committee Member); Neil Wells Ph.D. (Committee Member) Subjects: Paleontology

BA, Oberlin College, 2019, Geology

Sediments collect in reef lagoons, and the shells within these can record changes in the environment as they accumulate. Smuggler's Cove (St. Croix, USVI) has been accumulating a sediment package for at least 5,000 years based on radiocarbon ages. Callianassid shrimp severely bioturbate this lagoon's sediment package by moving shell material into shelly, subsurface lags that have a high chance of becoming fossilized. Shell condition (taphonomy) was compared between surface and lag to see whether the lag is an accurate representation of the living surface fauna. Guild membership, taxon, and mollusk size between surface and lag assemblages were analyzed. It was found that the surface beds were more similar to each other than to lags regardless of habitat, and subsurface beds were also more like one another. The dominance of infaunal guilds and the scarcity of epifaunal guilds in the subsurface suggests that it is difficult for callianassids to bring down surface shells. The decrease in taphonomic alteration in the lower beds suggests that shrimp are not pulling shells down by size alone but rather by life guild, favoring infaunal over epifaunal organisms. Since infaunal organisms are less subject to taphonomic alteration than epifaunal ones and tend to be small, guild membership is driving the overall taphonomic signal and influences the results for species and size. Therefore, infaunal species may be overrepresented in the fossil record in these types of environments. The epifaunal surface shells on the other hand, may persist there until degraded into sand.

Committee: Karla Parsons-Hubbard (Advisor); Steven F. Wojtal (Committee Member); Dennis K. Hubbard (Committee Member) Subjects: Geology; Paleoecology; Paleontology

Doctor of Philosophy, University of Akron, 2018, Integrated Bioscience

Melanins are a class of ubiquitous pigments that provide not only coloration to the organisms in which they produced, but also serve as a mechanism for thermoregulation, protection from ultraviolet radiation and cytotoxicity induced by free radicals, as well as numerous other beneficial roles. In most animals, melanins are housed in organelles called melanosomes. Melanosome morphology correlates with melanin-based coloration in birds and mammals, but melanosome diversity is limited in basal amniotes. Approximately 10 years ago, the study of melanosomes, melanin, and coloration was extended to the fossil record by the reinterpretation of microbodies preserved in fossil feathers initially interpreted as bacteria as remains of melanosomes. However, despite countless lines of evidence for this hypothesis that have been described since, some authors argue that the bacterial hypothesis is equally parsimonious. This dissertation will address some of the concerns of purveyors of the bacterial hypothesis and discuss the evolutionary history of melanosomes and melanins. We first tested the hypothesis that striped fossil feathers are the result of bacterial preservation through taphonomic experimentation. We found that modern keratinolytic bacteria preferentially colonize unpigmented stripes in modern feathers over melanized stripes, so it is unlikely that this hypothesis was supported in ancient ecosystems. We also found that bacteria and biofilms preserved in association with fossil integument are dissimilar to microbodies interpreted as fossil melanosomes. We began the second part of this dissertation by describing an enantiornithine bird that exhibits a mix of juvenile skeletal characteristics and sexual ornaments. Melanosomes preserved in its feathers are similar in morphology and arrangement to those in modern iridescent feathers, which are predominantly used to attract mates. We also described melanosomes associated with the fossilized skin of amphibians and lamp (open full item for complete abstract)

Committee: R. Joel Duff Ph. D. (Advisor); Matthew Shawkey Ph. D. (Committee Member); Liliana D'Alba Ph. D. (Committee Member); Julia Clarke Ph. D. (Committee Member); John Senko Ph. D. (Committee Member) Subjects: Paleontology

MS, University of Cincinnati, 2016, Arts and Sciences: Geology

Fossil assemblage faunal compositions may vary through space and time in response to climatic and/or taphonomic factors, but these relationships can be difficult to diagnose and disentangle. Here, we investigate how to disentangle climatic and taphonomic signals of a land-snail-rich volcanic scoria sequence to asses if it was influenced by taphonomic bias, climate change, or both, using a multifaceted approach, combining taphonomic, ecological, body-size, and stable-isotope data. Fossil assemblages were sampled from two beds (Units A and B) in a Pleistocene cinder cone volcano of southern Tenerife (Canary Islands), dated to the glacial interval MIS 8 (~299-302 ka). The two units differed in taphonomy, species composition, and abundance distributions. The upper unit, B (6 species), showed higher snail diversity and shell concentration and lower taphonomic alteration than the lower unit, A (3 species). Furthermore, larger bodied species (length>10mm) dominated Unit A and were better preserved than smaller species (length<10mm), whereas smaller individuals were more abundant (and better preserved) at Unit B. These differences were likely impacted by physical differences in the matrices surrounding the fossils. Unit A is comprised of larger scoria while Unit B contains small-to-medium-sized scoria and fines upward into a paleosol. Grain size of the scoria matrix therefore seems to affect species preservation, with larger clasts exposing snails to more severe postmortem agents and thus favoring the interstitial preservation of larger-size taxa. Comparisons with modern assemblages from the coastal scrub, the plant biome in which the Pleistocene site currently resides, indicates that no modern analogue exists for these fossil assemblages. Shell oxygen isotope values reveal that the climate shifted from colder/wetter during MIS 8 to warmer/drier at present, which may explain variations in species composition and diversity through time. These data suggest that both taphonomi (open full item for complete abstract)

Committee: Arnold Miller| (Committee Co-Chair); Yurena Yanes| (Committee Co-Chair); Joshua Miller (Committee Member) Subjects: Paleontology

MS, Kent State University, 2014, College of Arts and Sciences / Department of Earth Sciences

A recently-discovered Late Jurassic Lagerstatte in central Poland has yielded over 100 specimens of xiphosurids within limestones representing a storm or tsunami deposit. The species, Crenatolimulus darwini (Kin and Blazejowski, 2014) is reevaluated, which is the first record of the genus in Europe. The Polish specimens exhibit varying degrees of disarticulation and many are broken, which is interpreted to be a result of being tossed about during a mega-storm event; they otherwise demonstrate exceptional detail and preservation. Taphonomic experiments have been conducted on non-mineralized molts of the modern analog, Limulus polyphemus Muller, 1785, that were reintroduced to oxic sea water in order to determine the length of time it can take for molts to disarticulate when vigorously tumbled, simulating sea water movement during a mega-storm. Previously dried molts are analogous to those that have been washed ashore by wave activity and later returned to the sea, and these regain pliability after being reintroduced to water. Other experiments were conducted noting the length of time needed for molts to disarticulate while resting on an oxic ocean floor, excluding bioturbators and scavengers, as well as the effects of compression that lead to prosomal wrinkling. Results indicate that Polish horseshoe crab molts were likely to have disarticulated and broken before being displaced during a storm, and were not buried for days to months after molting their exoskeletons. Additionally, the presence of epibionts on horseshoe crabs is often indicative of age in modern species. Juveniles molt and burrow more frequently than adults do, and are less likely to carry epibionts. Serpulid worms were observed infesting many of the specimens from Poland, across all horseshoe crab prosomal sizes within the study sample. Although they are small in size compared to modern adult Limulus polyphemus, the Late Jurassic specimens are most likely mature. Crenatolimulus darwini has been placed (open full item for complete abstract)

Committee: Dr. Rodney Feldmann (Advisor); Dr. Carrie Schweitzer (Committee Member); Dr. Neil Wells (Committee Member) Subjects: Geology; Paleontology

BA, Oberlin College, 2000, Geology

In 1993 and 1994, the Shelf and Slope Experimental Taphonomy Initiative (SSETI) deployed thirty-five samples of sea urchins along the continental shelf/slope of the Bahamas in an effort to explore the paleoecology and taphonomic potentials of shallow water carbonate environments. Samples were retrieved at 1-, 2-, and 6-year intervals for examination and comparison of epibiont accumulation. Tests and spines of the sea urchin Eucidaris were examined for encrusting cheilostome Bryozoa. Specimens were identified to the genus level. Assessment of abundance and distribution patterns with water depth shows that cheilostomes are prevalent in photic waters, and lacking at depth. Burial of substrates limits bryozoan settlement patterns in shallow waters but not below the photic zone. Preliminary results indicate that cheilostomes may be useful biomarkers, at least in modern environments.

Committee: Karla Parsons-Hubbard (Advisor) Subjects: Geology

MS, Kent State University, 2014, College of Arts and Sciences / Department of Earth Sciences

The Late Cretaceous (Maastrichtian) Coon Creek Formation of Mississippi and Tennessee possesses a diverse and abundant assemblage of decapods including lobsters, ghost shrimp, and crabs. The formation lies in a temporally and paleogeographically significant location, situated between the Atlantic Coastal Plain and the Western Interior Seaway, shortly before the closing of the seaway and the K-Pg Mass extinction. Coon Creek decapods have been little studied since the fauna was first described in the 1920's. A large collection of specimens, ranging in preservation from poor to excellent, has recently become available for study. Because of the visible variation in preservation, the abundant material, and the paucity of cuticular data of this type of preservation, an investigative study of elemental composition of the sediment and cuticle of six species of decapod from six families (Palinuridae, Nephropidae, Callianassidae, Dakoticancridae, Raninidae, and Retroplumidae) is conducted using material collected at the Blue Springs Locality in Mississippi. Cuticle, concretions, decapod burrow, and sediment from the site are analyzed with X-Ray Florescence and Elemental Reflectance for preliminary elemental composition and subsequent mineral composition. Concretions and the burrow were observed in thin section and were mapped for elemental distribution using Energy-dispersive X-Ray spectroscopy and dot mapping. The six species of decapod were analyzed using the same techniques. Taphonomic data supports preservation ranging from well preserved phosphatization to secondary alteration to silica-rich exterior and weathering clay minerals. Because the silica is not replacing the phosphatized exocuticle and microscopic structure of cuticle in cross section is not preserved in the silica layer, the cause of this alteration is uncertain. This preservation is un-like the decapod cuticle preservation of the concretions of the Bearpaw Shale Formation (Late Cretaceous) of Montana. (open full item for complete abstract)

Committee: Rodney Feldmann Dr. (Advisor) Subjects: Earth; Geology; Paleoecology; Paleontology

MS, University of Cincinnati, 2014, Arts and Sciences: Geology

A Lagerstatte of Glyptocrinus decadactylus collected from the Upper Fairview Formation at Maysville, Kentucky, USA, yields new insights into the paleoautecology of camerate crinoids of the Late Ordovician. The Lagerstatte represents an autochthonous community comprised of a single mudstone interval representing an obrution deposit and containing over 400 individual glyptocrinids, including over 250 calyces. The crinoids had colonized a rise of relatively high energy within the deep subtidal zone where they were partially sheltered by plant matter to which they were attached, as suggested by columns terminating distally in coiled holdfasts of relatively consistent diameter. Turbidity flows originating in storm events led to the suspension of fine sediments by a lofting plume that intruded into and buried the crinoids in their habitat. The crinoid and plant stand on the rise may have created additional friction that slowed the sediment plume and induced deposition, signifying burial facilitated by a feedback process. Some specimens had been dead for a period of time prior to burial, suggesting more than one earlier killing event, likely related to the storms that ultimately caused the obrution. Other specimens were apparently killed by the obrution event and subjected to little or no scavenging in the resulting anoxic conditions, leading to excellent preservation. Most specimens are in trauma position, although more than 6% were preserved in spread-fan feeding posture, aboral surface up. The latter position is indicative of very rapid burial, and is often seen in stalked crinoids capable of neither crawling nor autotomizing their stems to escape. The high density of the crinoid community was accommodated by tiering, in which, in addition to the plant matter, the crinoids employed the columns of earlier-settled specimens as attachment sites; differing column lengths positioned the crinoids at various levels within the community. Further strategy for enduring crow (open full item for complete abstract)

Committee: David Meyer Ph.D. (Committee Chair); Brenda Hunda Ph.D. (Committee Member); Carlton Brett Ph.D. (Committee Member) Subjects: Paleontology

Master of Science (MS), Bowling Green State University, 2013, Geology

The Late Pleistocene-Early Holocene of Ohio was a period of dynamic changes in climate, flora, and fauna. Climate and flora studies have been greatly aided by palynology research in Ohio's prevalent peat deposits but faunal dynamics, particularly for large (≥ 44 kg) mammals, are less certain. Available Pleistocene-aged fossils are limited and existing databases are largely incomplete. This study adds to the available data through the creation of the Ohio Pleistocene Mammal Database (OPMDB). The database is composed of fossil finds within Ohio of probable Pleistocene age that have been collected from historic sources, i.e., period newspapers, science journals, etc., and compiled into a geographically referenced database. Within this thesis, I describe the scope and breadth of the OPMDB and present preliminary taphonomic and geospatial analyses using the OPMDB. Initial results are consistent with those previously described in the scientific literature, supporting the view that historical reports can be reliable sources for information about fossil mammal occurrences. Clear differences in spatial distribution and preservational potential exist among Late Pleistocene-Early Holocene mammals. Analysis of the distributions of preserved species and individual skeletal elements by sedimentary context revealed that the greatest variety of taxa is preserved in peats. Mastodons dominate Ohio fossil localities, making up 56% of occurrences in the OPMDB, with sites spread throughout the state. Mastodons are found in a variety of depositional contexts, from peats and clays to gravels. In contrast, mammoths are relatively rare in peats and clays, and none are known from the lake plain of northwest Ohio. The peccary record is notably rich, with many complete skeletons; peccaries are most likely to be found in fluvial sands and silts. Other ungulates, including equids, cervids, and bovids, are most often represented in the OPMDB by isolated cranial material (teeth, horns/antlers, (open full item for complete abstract)

Committee: Margaret Yacobucci Dr (Advisor); Peter Gorsevski Dr (Committee Member); Jeff Snyder Dr (Committee Member) Subjects: Animals; Archaeology; Geographic Information Science; Geology; Paleoecology; Paleontology; Zoology

MS, University of Cincinnati, 2001, Arts and Sciences : Geology

Storms such as hurricanes can dramatically impact a coral reef. In November 1999, Hurricane Lenny traveled an unusual west to east path across the central Caribbean approximately 480 kilometers north of the island of Curacao. Reef damage surveys at 33 sites conducted just months after the storm documented occurrences of toppling, fragmentation, tissue damage, bleaching, and smothering due to the storm. Several factors influenced the degree of damage experienced by the reef, including the trend of the shoreline, coral growth form, colony size, and water depth. Curacao's location outside of the major hurricane belt and well south of the track of Hurricane Lenny shows that rarely disturbed reefs can incur significant damage by storm-generated waves that travel across a great distance. Pleistocene reef communities on the island preserve the same species of corals and reef zonation present on many modern reefs throughout the Caribbean. Transects conducted along the fossil reefs show that different reef paleoenvironments (reef crest vs backreef) have different relative abundances of components. These different environments also preserve corals in the position of growth to differing extents. Many large coral colonies are preserved in growth position with the presence of few or no encrusting or boring organisms. These observations suggest a very rapid burial, possibly associated with a major regression while the corals were still alive. Although storm features on modern reefs, such as toppling and fragmentation, may potentially be preserved in the Pleistocene reefs of Curacao, these features are difficult to differentiate from those that were produced by other natural day-to-day processes such as bioerosion and processes involved with a rapid regression, including large-scale movement of sands from nearshore beaches or dunes.

Committee: David Meyer (Advisor) Subjects:

PhD, University of Cincinnati, 2006, Arts and Sciences : Geology

The following series of papers addresses the need for a sequence stratigraphic model specifically designed for cratonic mixed carbonate-siliciclastic successions. Case studies are provided primarily from the mixed carbonate-siliciclastic strata of the Lexington Limestone of Kentucky. These studies explore the sub-regional and regional distribution of decameter-scale couplets composed of clean skeletal grainstone and argillaceous limestones interbedded with shales. Analysis of six couplets that make up the Lexington Limestone along a basin profile reveals that both parts of decameter-scale couplets are widely traceable, though each undergoes a gradual lateral facies change. Subsequent investigation reveals that these six couplets are regionally traceable along strike, showing particularly good similarity to age equivalent strata in New York. More detailed studies are also provided that focus on different aspects of the couplets to help reinforce their sequence stratigraphic significance. The uppermost skeletal grainstone unit of the Lexington Limestone and basal portion of the overlying Kope Formation are analyzed in great detail, incorporating stratigraphic correlation of individual beds between closely spaced exposures, sedimentology of condensed beds and discontinuity surfaces, and faunal and taphonomic gradient analysis of limestones within this interval. The data generated suggest that this grainstone-rich succession represents a deepening-upward succession formed during sea level rise, though with slightly varying degrees of influx of argillaceous sediments (lowstand, early transgression, and late transgression, respectively). Additional case-studies focus on the contact at the base of the grainstone-dominated half of the couplet. This contact, contrary to previous studies, is almost always sharp and erosional. In fact, detailed analysis reveals two closely spaced erosion surfaces, one at the contact of the two halves of the couplet (forced regression surface), (open full item for complete abstract)

Committee: Dr. Carlton Brett (Advisor) Subjects: Geology

MS, University of Cincinnati, 2004, Arts and Sciences : Geology

The Mother's Day Quarry contains the remains of a number of immature sauropod dinosaurs. This site is one of only a few thought to provide skeletal evidence of gregarious behavior in sauropods, but none of these sites has been taphonomically constrained in order to verify the presence of a herd remnant; our only reliable data on sauropod herds currently comes from the ichnological record, which often provides conflicting information. The Mother's Day site has the potential to clarify ambiguities in the trackway data. This study determines the suitability of the Mother's Day Quarry as a basis for behavioral interpretations. Analysis of the site reveals that post-mortem biases are minimal, and the sauropods in the quarry likely represent the remnants of a mobile social group. The absence of adult individuals in the assemblage is probably the result of age segregation of some sauropod herd groups.

Committee: Dr. Glenn Storrs (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2007, Geological Sciences

Complex, multicellular life underwent a global adaptive radiation in the lower to middle Cambrian (~542 Ma). The fossil record is dominated by hard part fossils, but rarely a site of exceptional preservation allows study of both organisms with hard parts and organisms composed of soft, non-mineralized tissue. The Burgess Shale Biota was the first fully described fossil assemblage in the Cambrian that contains a relatively complete picture of an ancient living benthic community. More and more Burgess Shale-type fossil assemblages have been discovered since then and are ready to be utilized to test hypotheses about the paleoecology of the Cambrian explosion, which is the most important event in the evolution of metazoans. The most significant discoveries have been made in China, including the early Cambrian Chengjiang Biota and the less well known middle Cambrian Kaili Biota, which is an important BST deposit bridging the stratigraphic gap between the Chengjiang Biota and the Burgess Shale Biota. The Kaili Biota is the primary focus of this dissertation, but other Proterozoic, Cambrian, and Ordovician material was also studied. This work is based on four field seasons in China, two of which were completed during doctoral studies. More than 1,200 specimens of well-preserved Cambrian and Proterozoic fossils were studied in detail. Results from my research include: 1) a comprehensive review on the discovery, significance, and social impact of the Kaili Biota for English-speaking readers; 2) a better understanding of both the Kaili Biota and the newly discovered Balang Biota of Guizhou and their sequence stratigraphic context; 3) a compilation of all geological studies on the Kaili Formation to reinforce its potential as a global stratotype; 4) detailed studies of the taphonomy of well-preserved arthropods and echinoderms and their implications to understand the diagenetic history of the Kaili Biota; 5) a new interpretation that the depositional environment of Kaili Biota (open full item for complete abstract)

Committee: William Ausich (Advisor) Subjects: Geology

Doctor of Philosophy, University of Akron, 2012, Integrated Bioscience

The modern synthesis of paleontology with evolutionary biology has successfully integrated population ecology into the study of the fossil record. While it may prove impossible to measure and account for the important processes that structure communities through time, the integration of community ecology into paleoecology remains to be done to further the modern synthesis. This dissertation attempts to integrate community ecology into the study of a lacustrine ostracode metacommunity across space today and through the mid Holocene on San Salvador Island, Bahamas. Patterns of community change across space today are investigated by comparing the live/dead agreement in taxonomic composition and rank-abundance of species in seven lakes. This taphonomic study establishes that live/dead agreement of ostracode assemblages is high in all lakes save one. Therefore, sampling of death assemblages, as is common in many paleolimnolgical studies, can be used to investigate changes in alpha and beta diversity of assemblages across time and space. Death assemblages were then sampled from thirty-two lakes on San Salvador to investigate the metacommunity dynamics that explain patterns of beta diversity of communities. I found that beta diversity was most strongly controlled by the local environment in which communities live with the change in communities most strongly correlated with changes in a complex hydrological gradient of: conductivity, dissolved oxygen, and alkalinity. After establishing that the metacommunity dynamics conformed to a species sorting model, I exploited the association between ostracode assemblages and conductivity to create a statistical model that used changes in ostracode assemblages to predict changes in conductivity within individual lakes on San Salvador. This model was then applied to archives of ostracode assemblages from the mid-Holocene to today to create a record of changing conductivity through time in three lakes. The model reveals large, hi (open full item for complete abstract)

Committee: Lisa E. Park Dr. (Advisor); Francisco B.-G. Moore Dr. (Committee Member); Jean J. Pan Dr. (Committee Member); John M. Senko Dr. (Committee Member); Alison J. Smith Dr. (Committee Member) Subjects: Paleoecology