DIVERSE ORGANIC-WALLED FOSSILS, INCLUDING POSSIBLE DINOFLAGELLATES, FROM THE EARLY NEOPROTEROZOIC OF ARCTIC CANADA

A shallow-water shale unit from the early Neoproterozoic Wynniatt Form ation, arctic Canada, preserves an unusually high diversity of organic -walled fossils, including abundant cyanobacteria, several multicellul ar protists and/or problematica, and more than 30 distinct acritarch s pecies. Recognition of 13 new acritarchs, based on novel ornamentation , excystment structures, and/or wall structure, substantially increase s their known diversity for this interval and points to a severe under sampling of the Proterozoic fossil record. Three of these new acritarc hs exhibit features characteristic of dinoflagellate cysts and are rea sonable candidates for early representatives of the clade, particularl y in light of recent molecular phylogenetic analyses and biomarker dat a. The high diversity of acritarchs in the Wynniatt Formation also bol sters the potential for biostratigraphic resolution in the Neoproteroz oic.