303 Brachiopods and molluscs from the Permian Arcturus Formation, Nevada and Utah

Brachiopods and molluscs from the Permian Arcturus Formation, Nevada and Utah - BAP #303 The Arcturus Group, early Permian, of eastern Nevada and western Utah contains the Riepe Spring Formation at the base, Riepetown Formation, Pequop Formation, and Loray Formation at the top, and ranges in thickness from less than 1000 meters to greater than 2000 meters. The base of the Arcturus Group is early Wolfcampian in the western and northern parts of the area, and middle Wolfcampian in the center of the depositional area. Deposition of sediments continued without significant interruption until the late Leonardian. The Leonardian-Guadalupian boundary occurs in the overlying Kaibab Formation. Normal salinity marine biotas are common throughout, and biotas representing hypersaline environments are present in the upperpart of the Arcturus Group. Biotas representing hyposaline (brackish) and fresh-water environments are not recognized and are probably absent. Arcturus Group biotas are dominate