title: Exceptional preservation of fossils in an Upper Proterozoic shale.
abstract: Late Proterozoic organisms must have been diverse and widely distributed, but in general their fossil record is both taxonomically and environmentally limited.  Exceptional preservation of Proterozoic fossils is not unknown, but it is usually associated with silicified carbonates from restricted peritidal or playa lake environments.  We report here an exceptionally well preserved and distinctive assemblage of Late Proterozoic fossils from subtidal marine shales.  In addition to the sphaeromorphic acritarchs and cyanobacterial sheaths routinely preserved in Proterozoic rocks, this assemblage includes multicellular algae ('seaweeds'), a diverse assortment of morphologically complex protistan vesicles, and probable heterotrophic bacteria.  Thus, it provides one of the clearest and most taxonomically varied views of Proterozoic life yet reported.
authors.affiliation: Botanical Museum, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: N J
authors.initials: NJ
authors.lastname: Butterfield
authors.forename: A H
authors.initials: AH
authors.lastname: Knoll
authors.forename: K
authors.initials: K
authors.lastname: Swett
mesh_terms: D001419:Bacteria / Q000145:classification*; D000458:Cyanobacteria; D004783:Environmental Microbiology; D056890:Eukaryota / Q000145:classification*; D005580:Fossils; D019015:Geologic Sediments / Q000382:microbiology; D009664:Norway; D009792:Oceans and Seas; D010163:Paleontology