Ordovician-Silurian graptolites, integrated stratigraphy, biodiversity history, and paleoenvironmental change

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** p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px 'Times New Roman'}**** p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px 'Times New Roman'}******* p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px 'Times New Roman'}******* p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px 'Times New Roman'}******* * 0* 0* 1* 382* 2179* STFX* 18* 5* 2556* 14.0* * * * *** * Normal* 0* * * * * false* false* false* * EN-CA* X-NONE* X-NONE* * * * * * * * * * * * * * * * * * * * * * * * ** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *** **** /* Style Definitions */*table.MsoNormalTable* {mso-style-name:"Table Normal";* mso-tstyle-rowband-size:0;* mso-tstyle-colband-size:0;* mso-style-noshow:yes;* mso-style-priority:99;* mso-style-parent:"";* mso-padding-alt:0cm 5.4pt 0cm 5.4pt;* mso-para-margin:0cm;* mso-para-margin-bottom:.0001pt;* mso-pagination:widow-orphan;* font-size:10.0pt;* font-family:"Times New Roman";}*******The Ordovician and Silurian periods (ca. 500-420 million years ago) were*times of dramatically changing climate, sea level, and biodiversity. One of the*biggest mass extinction events in Earth history occurred near the end of the*Ordovician Period. The most important group of animals preserved in the marine*plankton during these time periods was the graptolites, a group of mostly*extinct hemichordates. They were abundant, geographically widespread and*evolved rapidly, which makes them excellent fossils for identifying short*intervals of geologic time and correlation of those intervals around the globe.*A thorough understanding of these organisms and their distribution in*sedimentary strata maximizes our potential to use them to solve a wide range of*Earth science problems in areas such as tectonics, sedimentary basin history,*climate change, and long-term evolution of the world's oceans. My research*program has several major and ongoing objectives: 1) reconstruction of the*evolutionary history of graptolites; 2) understanding the history of change of*graptolite biodiversity as a result of changing rates of species origination*and extinction, particularly through the cycles of climatic and oceanic changes*that characterized the Ordovician and Silurian periods; and 3) studying the*physical and chemical record preserved in rock strata to better understand the*environmental cycles and their causes, particularly to gain insights into the*factors responsible for the Late Ordovician Mass Extinction. For the last objective,*I am particularly interested in the history of anoxia in the oceans – times*when large areas of the ocean became depleted in oxygen. I propose to examine*oceanic anoxia using sedimentary, paleontological and geochemical signals, and*investigate the formation and changing distribution of anoxia in terms of its*relationship to changes in climate, ocean circulation and biological*productivity. I will also integrate data from graptolite occurrences with the*geochemical record in sedimentary strata from several different parts of the*world to improve the precision with which we can define and subdivide*geological time. By improving the precision with which we can resolve*geological time, we can gain clearer insights into the timing and rates of*evolutionary, paleoenvironmental and geological processes. This research into*the long-term links among climate change, ocean circulation and biodiversity*will provide insights that will help us better understand the modern world of*changing climate and biodiversity.*** ** p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px