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2006

All Graduate Theses and Dissertations

Northwestern

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Historical Biogeography Of North American Nightsnakes And Their Relationships Among The Dipsadines: Evidence For Vicariance Associated With Miocene Formations Of Northwestern Mexico, Daniel G. Mulcahy May 2006

Historical Biogeography Of North American Nightsnakes And Their Relationships Among The Dipsadines: Evidence For Vicariance Associated With Miocene Formations Of Northwestern Mexico, Daniel G. Mulcahy

All Graduate Theses and Dissertations

I used a Hierarchical approach to study historical biogeography in a group of colubrid snakes found in western North America. I combined small regions of mtDNA sequence data from a large number of individuals, with complete mt-genomic data. First, I investigated the relationships among leptodeirines-a presumed subgroup of dipsadines includeng nightsnakes (Pseudoleptodeira, Eridiphas, and Hypsiglena) - using ~1.5 Kb of data (cob and nad4). The relationships differed among parsimony, likelihood, and bayesian analyses. All analyses supported the monophyly of the nightsnakes; however, none supported the monophyly of the leptodeirines. Instead, these data supported a new hypothesis that the dipsadines were ...


Lower Paleozoic Sequence Stratigraphy, Deposystems And Paleogeography Of Northwestern Ordos Basin, North China, Benjamin J. Kessel May 2006

Lower Paleozoic Sequence Stratigraphy, Deposystems And Paleogeography Of Northwestern Ordos Basin, North China, Benjamin J. Kessel

All Graduate Theses and Dissertations

The Ordos basin rests upon the North China Block and is one of the largest sedimentary basins in north China, with more than 15 km of Phanerozoic strata. Published estimates suggest that over 2000 m of carbonates and lesser amounts of siliciclastics were deposited on the North China Carbonate Platform (NCCP) from the Lower Can1brian through the Middle Ordovician. However, lower Paleozoic facies successions and deposystems of northwestern Ordos basin remain poorly represented in western literature. This paper constrains depositional environments, lithologies, facies relationships and sea-level history of the northwestern part of the North China block (NCB) in an effort ...