Organic-walled microfossils from the late Mesoproterozoic to early Neoproterozoic lower Shaler Supergroup (Arctic Canada): Diversity and biostratigraphic significance

•First paleontological investigation of the lower Shaler Supergroup, Arctic Canada.•Higher diversity of eukaryotic taxa, at the Meso-Neoproterozoic transition.•Five new ornamented and process-bearing acritarchs species.•Extended stratigraphic range of previously known taxa.•Earlier diversification of eukaryotes than previously reported.