@mastersthesis {34246,
	title = {Late Cambrian and earliest Ordovician trilobites, southern Canadian Rocky Mountains, Alberta},
	year = {1984},
	address = {University of Toronto},
	abstract = {The Upper Cambrian Bison Creek and Mistaya formations represent the shaly and carbonate half-cycles of a sedimentary Grand Cycle in Banff and Jasper parks, Alberta. Five recurrent lithologic associations are defined. Three Bison Creek associations record deposition in a storm-dominated, subtidal shelf setting. Two associations from the Mistaya Formation were deposited in subtidal and peritidal environments. The Grand Cycle records rapid progradation of a carbonate bank complex across a shallow, subtidal, storm-dominated shelf.

175 collections yielded more than 9000 trilobites. Size-sorting as a source of sample bias in storm deposits is examined in three biostratinomic models. Twelve trilobite biofacies are defined from generic relative abundance data and several of these are present in other regions. At trilobite extinction events, very few, environmentally widespread biofacies are recognised. Maximum biofacies differentiation and reduced environmental ranges occur in the Saukia Zone.

Two new Upper Cambrian stages are used. The Steptoean Stage is equivalent to, and replaces, the Pterocephaliid Biomere. The Sunwaptan Stage is equivalent to, and replaces, the Ptychaspid Biomere. The zonal scheme of seven zones and eighteen subzones or informal faunas established for the Late Steptoean to lowest Ibexian in Alberta may be correlated with parallel schemes for other parts of North America.

Trilobite extinctions at the close of the Sunwaptan Stage are associated with major environmental changes in the outer part of the shelf only and occur through stratigraphic intervals of up to 25m. A biogeographic model predicts that extinctions will be related to a reduction in levels of biofacies differentiation and is supported by biofacies changes at ten sites in North America. The geographic/biogeographic shifts which lead to the extinctions may have been initiated by a relative sea level rise.

New genera are: Calvipelta, Kathrynia, Prioricephalus, Pugionicauda, Sunwaptia and Wilcoxaspis. New species are: Acheilops montis, Briscoia angustilimbus, Calvipelta spinosa, Conococheaguea? ludvigseni, Croixana inflata, Dellea rasilis, Drabia occidentalis, Eurekia longifrons, Heterocaryon vargus, Illaenurus holcus, Kathrynia limbata, Kendallina? crassitesta Monocheilus orestes, Orygmaspis (Parabolinoides) calvilimbatus, O. (Parabolinoides) spinula, O. (Parabolinoides)? triangularis, Plethometopus glaber, Plethometopus hastatus, Proricephalus wilcoxensis, Pugionicauda paradoxa, Stigmaspis albertensis, Sunwaptia carinata and Wilcoxaspis bulbosa. New suprageneric taxa are: Macronodinae and Ellipsocephaloididae.},
	url = {http://search.proquest.com/docview/303332830},
	author = {Westrop, Stephen Richard}
}
