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Full-Text Articles in Paleontology

Incorporation, Morphology, And Extinction Of Framework-Building Metazoans In Early Cambrian Reef Ecosystems From The Western Usa And Mongolia And Their Effects On Reef Diversity, David Russell Cordie May 2019

Incorporation, Morphology, And Extinction Of Framework-Building Metazoans In Early Cambrian Reef Ecosystems From The Western Usa And Mongolia And Their Effects On Reef Diversity, David Russell Cordie

Theses and Dissertations

The early Cambrian represents an important transition in the evolution of life, perhaps most vividly exemplified by reef ecosystems as they changed from microbial-supported to metazoan-supported framework reefs. Microbial reefs were initially composed of Renalcis- and Epiphyton-group calcifying microbes. Subsequent reefs began to incorporate archaeocyathan sponges within this framework. This represents a shift in the source of carbonate production, which can be quantified using thin section point counts. In archaeocyathan reefs from the western USA, carbonate contribution from metazoan framework builders increased from zero to 29.7%. Similar reefs from Mongolia increased from zero to 5.0%. Increases in Laurentian archaeocyath contributions …


Death-Defying Morphologies: Mass Extinction And Disparity In The Order Harpetida, James Desmond Beech Jan 2019

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 …