Studies in Proterozoic paleobiology from Spitsbergen and Arctic Canada

Fossil assemblages from Spitsbergen, Baffin Island, and Somerset Island provide a much enhanced view of Proterozoic paleobiology. Shallow water shales, cherts, phosphorites, and carbonates in the 700-800 Ma Svanbergfjellet Formation, northeastern Spitsbergen, preserve 65 distinct fossil forms, including 4 species of multicellular green algae (Siphonocladales and Chlorococcales), 3 multicellular taxa of unknown taxonomic affiliation, 19 acritarch species, and numerous cyanobacteria and insertae sedis. An analysis of fossil taphonomy offers some useful taxonomic distinctions, but generally points to a pervasive 'over-splitting' of form taxa; several major taxonomic revisions are proposed. The Svanbergfjellet fossils contribute significantly to the understanding of early multicellularity and to an increasingly detailed Neoproterozoic biostratigraphy.; A shale sample from the Black Shale Member of the ca. 1250 Ma Agu Bay Formation (Fury and Hecla Group), northwestern Baffin Island, is dominated by small leiosphaerid acritarchs. Their very even distribution on bedding planes and a dearth of typical shallow-water forms (e.g., filaments, large and/or ornamented acritarchs) suggest an offshore deposition in water sufficiently deep to preclude a photosynthesizing benthos; a mid to outer shelf setting is supported by the local sedimentology. A review of Proterozoic fossil distribution permits the delineation of 5 depth-dependent paleoecological zones extending from restricted nearshore to basinal environments. Such recognition serves as a valuable measure of paleoenvironment and should substantially refine any biostratigraphic signal.; Silicified peritidal carbonates from the 1270-725 Ma Hunting Formation on Somerset Island (arctic Canada) contain fossils of a well preserved bangiophyte red alga, Bangiomorpha antiqua n. gen., n. sp. Evidence of transverse intercalary cell division in uniseriate filaments, and a subsequent longitudinal division to yield multiseriate filaments of radially-arranged wedge-shaped cells, shows it to be closely allied to modern Bangia. Together with the Svanbergfjellet chlorophytes, the Hunting fossils push the record of taxonomically resolved metaphytes well back into the Proterozoic.