Early to Middle Jurassic non-marine bivalve Ferganoconcha and its palaeogeographic and palaeoenvironmental implication.

The non-marine bivalve Ferganoconcha occurred widely in palaeolakes in the high-middle latitude of northern China, Siberia and Central Asia during the Early and Middle Jurassic and was an important member of these lacustrine ecosystems. The diagnostic features and phylogenetic position of Ferganoconcha are still under debate. Here, based on nearly one hundred of Ferganoconcha specimens from the lacustrine and fluvial facies of the Junggar Basin in northwestern China, it is clearly shown that its most important distinctive features are the thin and flatted to weakly inflated shell covered with wrinkled ornament and the ligament is well-developed. This kind of shell indicate that the Ferganoconcha is a weak suspension feeder, burrowing rapidly and living in fine-soft substrata of the 'low energy' environments. In addition, we conclude that the dispersal pattern of the Ferganoconcha generally followed the cool to temperate and humid paleoclimate zone in northern China during the Early to Middle Jurassic, making the genus a possible palaeclimatic indicator. [ABSTRACT FROM AUTHOR]