Diverse organic-walled fossils, including “possible dinoflagellates,” from the early Neoproterozoic of arctic Canada

A shallow-water shale unit from the early Neoproterozoic Wynniatt Formation, arctic Canada, preserves an unusually high diversity of organic-walled fossils, including abundant cyanobacteria, several multicellular protists and/or problematica, and more than 30 distinct acritarch species. Recognition of 13 new acritarchs, based on novel ornamentation, excystment structures, and/or wall structure, substantially increases their known diversity for this interval and points to a severe undersampling of the Proterozoic fossil record. Three of these new acritarchs exhibit features characteristic of dinoflagellate cysts and are reasonable candidates for early representatives of the clade, particularly in light of recent molecular phylogenetic analyses and biomarker data. The high diversity of acritarchs in the Wynniatt Formation also bolsters the potential for biostratigraphic resolution in the Neoproterozoic.