In Search of the Cretaceous-Tertiary Boundary in Heilongjiang River Area of China

A new geological section recognized in Baishantou of Jiayin,Heilongjiang Province,China,was studied preliminarily in searching for the K/T boundary.An early Paleocene florule characrerized by abundant Tiliaephyllum tsagajanicum leaves and its associated plants,was collected from the Baishantou Member(new member representing the lower part of the Paleocene Wuyun Formation)overlying the possible K/T boundary.A tuff bed was found from the upper part of the Furao Formation(uppermost Cretaceous)in this section.The new findings imply that the K/T boundary is probable lying in the interval between the base of the Baishantou Member and the tuff bed,based on the correlation of the present strata with the stratotype of the Tsagajan Group spanning the K/T boundary in"Belaya Gara"of the Bureya Basin,Russia.The early Paleocene florule from the Baishantou Member and the early-middle Maastrichtian dinosaurs found from the Yuliangzi Formation underlying the Furao Formation suggest that the Baishantou section is more promising for searching for the K/T boundary in this area.Further studies of the section is needed,integrating paleontological,biostratigraphic,geochemical,paleomagnetic,and sedimentary research would benefit our understanding the mass extinction event and biotic recovery in the Heilongjiang River area,China,and even all of northeast Asia during the K/T boundary interval.

Recent advances on study of hadrosaurid dinosaurs in Heilongjiang(Amur) River area between China and Russia

Four main dinosaur-bearing sites have been investigated in latest Cretaceous deposits from the Amur/Heilongjiang Region ： Jiayin and Wulaga in China （ Yuliangze Formation）, Blagoveschensk and Kundur in Russia （Udurchukan Formation）. More than 90% of the bones discovered in these localities belong to hollow-crested lambeosaurine hadrosaurids： Charonosaurus fiayinensis at Jiayin, Amurosaurus riabinini at Blagoveschensk, Olorotitan arharensis at Kundur, and Sahaliyania elunchunorum at Wulaga. Flat-headed hadrosaurine hadrosaurids are much less numerous, but appear well diversified as well： Kerberosaurus manakini at Blagoveschensk, Wulagasaurus dongi at Wulaga, and a new genus at Kundur. Theropods are represented by shed teeth and isolated bones; isolated scutes and teeth discovered at Kundur are tentatively attributed to nodosaurids. Palynological studies suggest that these sites are probably synchronous with the Lancian＇ vertebrate localities of western North America, which represent the youngest dinosaur faunas in this area. However, the latest Cretaceous dinosaur assemblages are completely different in the Amur/Heilongjiang region （lambeosaurines abundant, ceratopsids absent） and in western North America （ceratopsids abundant, lainbeosaurines extremely rare or absent）. This probably reflects some kind of geographical barrier between both areas by Maastrichtian time rather than strong differences in palaeoecological conditions.