Fig. 1 Geological map of the Vilui Basin (after3 Vachrameev & Pushczarovskii 1954). The Sangar Group (dotted) includes Lower Cretaceous strata. The Vilui Group includes the latest Albian to Maastrichtian Timerdyakh FM (medium gray and the Maastrichtian and possibly early Tertiary Linde FM (light grey). The ages of the formations are constrained by palynological and palaeobotanical data4-6 (Vachrameev 1958, Bolkhoditina 1959, Semoylovich 1965