Evolutionary and biogeographic patterns of trilobites during the end Ordovician mass extinction event | Posted on:2009-03-20 | Degree:M.A | Type:Thesis | University:University of Kansas | Candidate:Congreve, Curtis R | Full Text:PDF | GTID:2440390005957188 | Subject:Geology | Abstract/Summary: | | The end Ordovician mass extinction event is believed to have been caused by a geologically brief, sudden onset glacial period that interrupted a period of extreme greenhouse conditions. The cause of this icehouse is a matter of contention, but recent a recent work proposes that a nearby gamma-ray burst could have affected the Earth's atmospheric chemistry and pushed the climate from a greenhouse into an unstable icehouse. Survivorship patterns of trilobites and their larval forms appear to agree with this theory. In order to further explore the Ordovician extinction, I conducted three individual paleontological studies to test macroevolutionary and biogeographic patterns of trilobites across the extinction. The first study is a phylogenic and biogeographic analysis of the family Homalonotidae Chapman 1890, the second is a similar analysis of the subfamily Deiphoninae Reed 1913, and the third is a GIS study of species ranges of the subfamily Deiphoninae. | Keywords/Search Tags: | Extinction, Ordovician, Biogeographic, Patterns, Trilobites | | Related items |
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