In 2008–2011, a team of German and Chinese paleontologists discovered and studied an "enormous" accumulation of Jurassic turtle fossils at a site they nicknamed "Mesa Chelonia", approximately NNE of Shanshan Town. It is estimated that at least 1,800 skeletons of freshwater turtles, preliminary identified as belonging to the "Annemys" species were buried in this bone bed, in a stratigraphic layer probably belonging to the Qigu Formation. The researchers suggest that during a drought the turtles congregating at one of the few remaining water sources, and died there once that last water hole dried out. Then the skeletons were transported to the present location by a debris flow during a catastrophic rainfall event, forming a "Konzentrat-Lagerstätte".