Habitat of the Early Cretaceous non-marine bivalve Nippononaia yanjiensis in northeast China

The Lower Cretaceous Sunjiawan Formation of northeast China consists of non -marine deposits containing abundant Nippononaia yanjiensis Gu. These sedim entary rocks comprise fluvial channel and overbank (levee, crevasse splay, pond and floodplain) accumulations. There are two modes of occurrence of N. yanjiensis. Type 1 is characterized by inferred life positions within the pond deposits, and Type 2 represents poorly preserved fragments and disarti culated valves within the channel deposits. N. yanjiensis was a freshwater mollusc that lived in ponds within abandoned channels in overbank environme nts. The genus Nippononaia is widely distributed in the Northern Hemisphere , and is a useful indicator of Lower Cretaceous freshwater environments. (C ) 2000 Academic Press.