The Neoproterozoic geological timescale (after Halverson et al. 2020). Negative carbon isotope anomalies/excursions provide useful chronostratigraphic references for subdivisions of the Neoproterozoic timescale: BSA, Bitter Springs Anomaly; RA, Russøya anomaly; GA, Garvellach anomaly; TA, Trezona Anomaly; SE, Shuram Excursion; BACE, Basal Cambrian Carbon Isotope Excursion. Minimum biostratigraphic ranges are also shown for Trachyhystrichosphaera aimika, Cerebrosphaera globosa (C. buickii), and the Cycliocyrillium simplex assemblage. Available absolute age constraints spanning the Cryogenian have multiplied in recent years and provide globally consistent estimates for the ages of the onset and end of the Sturtian and Marinoan glaciations. Here we show directly or closely stratigraphic radiometric age constraints using three approaches (volcanic zircon or baddeleyite U–Pb ages determined by isotope dilution thermal ionization mass spectrometry [ID-TIMS]; in-situ U–Pb ages determined by secondary ion mass-spectrometry [SIMS], sensitive high-resolution ion-microprobe [SHRIMP] or laser-ablation indicatively coupled plasma mass-spectrometry [LA-ICPMS]); and sedimentary Re-Os ages determined using ID-TIMS. Dashed lines indicate synglacial ages. Age compilation is modified from Halverson et al. (2020); Rooney et al. (2020) and Nelson et al. (2020).