Abstract
An abundant and diverse silicified fauna comprised mostly of gastropods, but including pelecypods, scaphopods, chitons, small orthoconic nautiloids, sponges, ostracodes, a trilobite species, and foraminifers, occurs in association with the alga Mizzia in a structurally isolated portion of the upper Bird Spring Group (BSe Unit). At least three gastropod species, Amaurotoma zappa, Glyptospira arelela, and Anomphalus jaggerius, are new. The assemblage resembles, in some respects, that described by Chronic (1952) from the Kaibab Formation (Leonardian-Guadalupian) of Arizona as well as undescribed assemblages from the Loray Formation (upper Leonardian) of eastern Nevada and the Bird Spring Group (middle Wolfcampian ?) of the Providence Mountains in southwestern Nevada. The fauna is tentatively assigned an uppermost Wolfcampian age on the basis of Schwagerina cf. S. crassitectoria Dunbar & Skinner, which occurs several hundred feet above the mollusk-bearing bed, as well as on the occurrence of Mizzia cf. M. yabei (Karpinski), previously reported from Middle to Late Permian rocks. Color markings are preserved on some of the gastropods, a chiton and a nautiloid.
Published Version
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