Paleoecology, Biogeography and Systematic Paleontology of Ordovician Sponges from Eastern Canada and Western United States

点击翻译按钮获取中文摘要

Early Paleozoic poriferans of the Western Hemisphere are among the least known of fossil invertebrate phyla, even though they are important constituents of reefs and inter-reef faunas, and even though North America seemed to have functioned as a major center of sponge evolution during the early Paleozoic. Objectives of the research are to publish monographic and synthesis papers on major Lower and Middle Ordovician faunas, from North America, including those from classic stratigraphic sections in western Newfoundland and from the Mingan Islands of eastern Quebec. These faunas are from the northern part of the Appalachian-Maritime region, which was on the southeastern margin of the Ordovician paleocontinent. Other major faunas to be studied are from Lower and Middle Ordovician rocks in the Confusion Range (Ibex area) of western Utah, and from equivalent rocks of the Toquima Range-Eureka-Ruby Mountain are of central and east-central Nevada. These latter faunas represent those from the northwestern margin of the Ordovician North American paleocontinent. Fossil sponges to be studied were generally collected from measured stratigraphic sections that have been selected as type or reference sections and that characterize broad regions in North America. Fossils will be studied using standard thin-section and acetate-peel techniques because the originally siliceous skeletons have been largely replaced by calcium carbonate in most fossils in the collection. A few potentially etchable sponges have been collected from Utah and Nevada, and they will be processed in dilute acids. Even fragments of such sponges have proven to be important because they show skeletal details that are often obscure in calcareous preservations. Taxonomy, paleoecology, stratigraphic and paleogeographic distributions and potential for biostratigraphic zonation, along with evolution of the assemblages, will be treated in an effort to present uniform data and synthesis of the scattered and uneven literature.