Age of the Upper Cretaceous Nemegt Formation (Mongolia) on charophytan evidence

The assemblages of Charophyta from the Nemegt Formation (Upper Cretaceous) and some Paleocene deposits of Mongolia are compared to those from China, Europe and America. It appears that Charophyta are useful in stratigraphy of continental deposits. The present investigations provided new evidence of the age of the Nemegt Formation from Mongolia. The assemblage of this formation is intermediate between two Upper Cretaceous assemblages from the “Red Beds” from China. Comparisons with the Chinese, European and American assemblages indicate that the Nemegt Formation is not younger than the Lower Campanian, thus is older than it was supposed before. The state of preservation of the oogonia permit to draw some ecological conclusions.