CISURALIAN AMMONOID GENUS URALOCERAS IN NORTH AMERICA

Abstract

In North America, the ammonoid Uraloceras Ruzhentsev occurs in Cisuralian (Lower Permian) strata of the northern Yukon Territory, eastern Alaska, Ellesmere Island, southern British Columbia, and Nevada. From Sakmarian to Kungurian, species of Uraloceras occupied a narrow belt in the Northern Hemisphere (Boreal paleogeographical realm) that extended from the northern and northwestern margin of the Pangaean supercontinent southward to regions of present-day Siberia, the Ural Mountains, as well as Nei Monggol and Tibet. In the Yukon Territory, Nevada, Nei Monggol, and possibly Tibet, the association of Uraloceras with typically equatorial perrinitid ammonoids may represent a transition from “Boreal” occurrences in high latitudes to “Tethyan” of lower latitudes. Uraloceras nevadense n. sp. is described herein from Nevada and eastern Alaska.