Thesis (Ph. D.)--University of Michigan, 1981. / A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Botany) at the University of Michigan 1981.

Thesis (M.S.)--Bowling Green State University, 2008. / Document formatted into pages; contains ix, 72 p. : ill. Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Prepaging (vii) included in total paging. Typescript. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Abstracted in Dissertation abstracts, v. 18 (1958) no. 3, p. 1013-1014. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 126-128).

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Prepaging (vii) included in total paging. Typescript. Includes bibliographical references. Also available on the Internet.

No description available.

The Mustelinae (weasels, stoats, minks, and ferrets) are a subfamily of small, elongate-bodied mustelid carnivorans (Carnivora: Mustelidae) that originated during the Late Miocene. Mustelines are the most abundant group of carnivorans in the world today and are commonly found at Pleistocene-aged sites across their range; however, their lack of a more complete fossil record has left many questions regarding the evolution of early mustelines unanswered. Here we report a new occurrence of a musteline from the Early Pliocene age (4.9 – 4.5 Ma) Gray Fossil Site in northeastern Tennessee. Morphology of the P4 and M1 are consistent with the dental characteristics of Mustelinae, and thus this find represents the first reported pre-Pleistocene occurrence of a musteline in the eastern United States. Morphology of the specimens is distinct from the well-known Miocene ischyrictine mustelid Plionictis, but falls within the range of variation observed within the extant genera Mustela and Neovison. Linear measurements also fall within the size ranges of those genera. Distinguishing Mustela from Neovison based on morphological characters alone is very difficult and recent phylogenetic studies differentiating the two have been based exclusively on genetic evidence. Further study will hopefully allow us to place a confident identification on the musteline from Gray. The small, hypercarnivore niche of mustelines is one that was previously not recognized among fauna at the Gray Fossil Site, and improves our understanding of the site’s paleoecology.

No description available.

No description available.

Exceptionally preserved fossils—or fossils preserved with remains of originally non-biomineralized (i.e. soft) tissues—constitute a key resource for investigating the history of the biosphere. In comparison to fossils of biomineralized skeletal elements, which represent the majority of the fossil record but only a fraction of the total diversity that existed in the past, exceptionally preserved fossils are comparatively rare because soft tissues are rapidly destroyed in typical depositional environments. Assemblages of such fossils, nonetheless, have received special attention among scientists in multiple fields of Earth and life sciences because they represent relatively 'complete' windows to past life. Through such windows, researchers are able to reconstruct original biological features (e.g. soft tissue anatomies) of extinct organisms and to describe the structures and compositions of ancient soft-bodied paleocommunities. To accomplish these goals, however, researchers must incorporate background information regarding the pre- and post-burial histories of exceptionally preserved fossils. In this context, my dissertation focuses on the environmental settings, diagenetic conditions, geomicrobiological activities, and weathering processes, which influence the conservation of original biological features within exceptionally preserved fossils and control their occurrences in time and space. An improved understanding of these critical factors involved in exceptional fossil preservation will ultimately our advance our knowledge regarding the history of the biosphere and the Earth system as a whole. Each chapter of original research in this dissertation includes an innovative and distinct approach for studying exceptional fossil preservation. The second chapter describes environmental and geologic overprints in the exceptional fossil record, as revealed by a comprehensive statistical meta-analysis of a global dataset of exceptionally preserved fossil assemblages. Moving from global to specimen-based perspectives, the second and third chapters focus on minerals (products of geomicrobioloigcal, diagenetic, and weathering processes) and carbonaceous materials replicating exceptionally preserved fossils. The third chapter examines the causes of preservational variations observed among organophosphatic tubular shelly Sphenothallus fossils in the lower Cambrian of South China using an experimental approach. (Although Sphenothallus is not an exceptionally preserved fossil sensu stricto, its conservation of original organic matrix tissues in South China provides key insights into the preservation of carbonaceous material within fossils.) Lastly, the fourth chapter presents data acquired using various in situ nanoscale analytical techniques to test the hypothesis that microstructures within exceptionally preserved microfossils of the Ediacaran Doushantuo Formation of South China are some of the oldest putative cylindrical siliceous demosponge spicules in the fossil record. Collectively, these chapters describe environmental, authigenic, diagenetic, and weathering processes that affect exceptional fossil preservation, and highlight innovative methods and approaches for testing major paleobiologic and geobiologic hypotheses regarding exceptionally preserved fossils. / Ph. D.