Master of Arts, The Ohio State University, 1913, Graduate School

Committee: Not Provided (Other) Subjects:

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

Doctor of Philosophy, University of Akron, 2014, Biology

This doctoral dissertation reports the results of a multi-faceted investigation into the evolutionary dynamics of sexual systems over geologic time using the fossil record of the bivalved branchiopod crustacea in the Order Spinicaudata. The difficulty of assessing the sex of fossils (and by extension, the sexual system employed in extinct organisms) is widespread, and in those taxa that do show sexual dimorphism (e.g., ammonites, some arthropods, and vertebrates), reproductive mechanisms are often invariant, making assessments of reproductive evolution impossible. In this study, new techniques have been developed that will allow the identification of sexes in fossil crustaceans within the taxon Spinicaudata (“clam shrimp”): an enigmatic group of crustaceans with a unique bivalved carapace. Clam shrimp are well-represented in the fossil record, and have a broad array of reproductive types: dioecy (males + females), androdioecy (males + hermaphrodites) parthenogenesis (asexual females) and selfing hermaphroditism. These projects combine the wealth of information about the evolutionary transitions among these various reproductive types gleaned from studies of extant clam shrimp, with the rich representation of clam shrimp throughout the fossil record (from the Devonian to the modern day) to address two canonical hypotheses of reproductive evolutionary theory: (1) that unisexual species should be short lived and less speciose than their outcrossing counterparts and (2) that androdioecy is an unstable, transitionary system that should not persist over long periods of time. These studies provide much needed reviews of existing paleontological and biological research regarding the Spinicaudata, assess their taphonomic fidelity using a number of experimental techniques, develops and tests a morphometric protocol for identifying sexes in fossil populations and subsequently extends these shape comparisons using a large collection of fossil clam shrimp taxa from across the (open full item for complete abstract)

Committee: Stephen Weeks Dr (Advisor); Lisa Park Dr (Committee Member); Franscisco Moore Dr (Committee Member); joel Duff Dr (Committee Member); Peter Niewerowski Dr (Committee Member) Subjects: Biology; Evolution and Development; Limnology; Morphology; Paleontology; Zoology