Ediacaran fossils from the southwestern Great Basin, United States

Ediacaran fossils from the southwestern Great Basin may help constrain regi onal Vendian-Cambrian biostratigraphy and provide biogeographic links betwe en facies in this region and elsewhere. Locally, trace fossils suggest the Vendian-Cambrian boundary occurs within or below the upper third of the low er member of the Wood Canyon Formation. Ediacaran soft-bodied and tubular f ossils, including the frondlike fossil Swartpuntia and tubular, mineralized or agglutinated fossils similar to Archaeichnium, Cloudina, Corumbella, an d Onuphionella occur in the lowermost Wood Canyon Formation. Discoidal form s referred to Nimbia occur in both the lowermost Wood Canyon Formation and the underlying strata of the Stirling Quartzite. These fossils occur direct ly below Lower Cambrian trace fossils, including Treptichnus pedum, and con firm the persistence of the Ediacaran biota to near the base of the Cambria n. These faunas may also help strengthen previously proposed correlation sc hemes between the two main facies belts of the southwestern Great Basin (th e Death Valley and White-Inyo facies), because a nearly identical Vendian-l owest Cambrian succession of faunas occurs in both regions. Lastly, lack of cosmopolitan Ediacaran faunas in these strata suggests a paleobiogeographi c link between the southwestern U.S. and southern Africa in Vendian time.