Udurchukan Formation

The Udurchukan Formation is a palaeontological formation located in Amur Region, Far East Russia.1 Based on palynomorphs such as Wodehouseia spinata the Udurchukan is considered of Maastrichtian age. Inasmuch as W. spinata and Aquillapollenites subtilis are known, in America, only from the late Maastrichtian, the presence of these palynomorphs in the Udurchukan caused Godefroit to consider the unit and its lambeosaur dominated fauna to be coeval with the Lance and Hell Creek formations. However, research in the Songliao basin indicates Wodehouseia spinata is also known from the early (albeit not basal) and middle Maastrichtian of Asia. The latest view, appearing in the paper on comparative osteology of Edmontosaurus and Shantungosaurus, is that one Udurchukan locality, Kundur, is late early Maastrichtian and the other, Blagoveschensk, is early late Maastrichtian. The Udurchukan now appears somewhat older than the Lance and Hell Creek, albeit not by much.