Abstract

Most species of the middle and late Hettangian psiloceratid genus Sunrisites are endemic to the eastern Pacific, where they are common members of ammonoid assemblages. The Taseko Lakes map area in British Columbia yields diverse and well-preserved Sunrisites faunas which are formally described here for the first time. Three new species are recognized, S. brimblecombei, S. chilcotinensis, and S. senililevis. The new species require an extension of the morphological range of the genus to include forms that become moderately involute at large shell diameters. Signs of sexual dimorphism are apparent within all three new species of Sunrisites. This work extends the stratigraphic range of Sunrisites to include the latest Hettangian Rursicostatum Zone in North America. The distribution of Sunrisites suggests that the Hispanic Corridor, which linked the western Tethyan Ocean and the eastern Pacific, may have been open during the Hettangian. Furthermore, occurrences of the genus constrain the Hettangian position of several allochthonous terranes to the northeastern Pacific.

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