Abstract Most of the Precambrian (>538 Ma) fossil record, which includes the time before the onset of macroscopic multicellular life, consists of minute organically preserved remains of soft-bodied micro-organisms, i.e. non-pollen palynomorphs (NPP). These microfossils include single-celled prokaryotic or eukaryotic organisms, filamentous sheets and bacterial cellular aggregates, and occur in marine and lacustrine sediments through most of the Earth's history. Ancient NPP have informed our understanding of one of the biggest evolutionary steps in the history of life: the origin of the eukaryotic cell and the subsequent diversification of eukaryotic life before the evolution of macroscopic forms. The oldest widely accepted eukaryotic microfossils are large cells with opening structures and ornamentation from upper Paleoproterozoic units in China and India. NPP diversify through Meso- and Neoproterozoic Eras, notably recording the oldest multicellular life around 1 billion years ago. In the latest Neoproterozoic, during the advent of animal life, the NPP record allows us to study the cryptic evolution of animals while they were exclusively small and poorly or non-mineralized before the appearance of organisms with hard parts. We review the current understanding of the early eukaryotic evolution and major advances in Precambrian palaeontology through the lens of the NPP record in deep time.

Abstract Glaciogenic deposits of the Rapitan and Hay Creek Groups are exposed in the Tatonduk inlier of east-central Alaska and the western Yukon. The Rapitan Group ranges in thickness from c. 50 to 700 m with Fe-formation common in the upper 10 m. In the most distal settings, the Rapitan Group is separated from the diamictite of the Hay Creek Group by over 100 m of sandstone and siltstone; however, the Hay Creek Group contains large erosive surfaces and cannibalizing breccia, and rarely preserves strata between the two glaciogenic deposits. The diamictite of the Hay Creek Group is capped by a white- to buff-coloured dolostone with pseudo-teepee structures, bed-parallel, isopachous sheet-crack cements, and a depleted C-isotope signature. Late Neoproterozoic glacial deposits in the Tatonduk inlier were formerly assigned to the Tindir Group. To simplify the nomenclature in the northwestern Canadian Cordillera, the Tindir Group was abandoned and replaced with nomenclature consistent with that of the Windermere Supergroup in the Mackenzie Mountains. The mixed lithology and anchizone-grade metamorphism distinguish the Rapitan and Hay Creek Groups in the Tatonduk inlier as attractive future targets for integrated micropalaeontology, geochemistry, palaeomagnetism and geochronology.