The new genus Tulepyge includes a type species, T. tulensis nov., from the Barn Canyon Member of the House Formation, western Utah, USA, and T. paucituberculata from the Broom Point Member of the Green Point Formation, western Newfoundland, Canada. Both species are earliest Ordovician in age, with occurrence immediately above the Cambrian-Ordovician boundary. Together with the hystricurid taxon Millardicurus, the new genus is likely to serve as an indicator fossil for the Cambrian-Ordovician boundary in Laurentia, as it is already known from different biofacies on opposite margins of the continent. Tulepyge is not closely comparable with contemporaneous taxa assigned to Hystricuridae but in its dorsally convex and coarsely tuberculate exoskeleton it resembles taxa which have been referred to Dimeropygidae, most of which are considerably younger in age.

Key words: Trilobita, Dimeropygidae, Hystricuridae, silicified fossils, Ordovician, Ibexian.

Jonathan M. Adrain jonathan-adrain@uiowa.edu, Department of Geoscience, University of Iowa, Iowa City, Iowa 52242, USA; Stephen R. Westrop swestrop@ou.edu, Oklahoma Museum of Natural History and School of Geology and Geophysics, University of Oklahoma, 2401 Chautauqua Avenue, Norman, Oklahoma 73072, USA.