supported by Natural Science Foundation of Guangxi (Grant No. 2013GXNSFAA019284);State Key Laboratory of Palaeobiology and Stratigraphy (Grant No. 123104);National Natural Science Foundation of China (Grant No. 41162002)~~
State Key Laboratory of Palaobiology and Stratigraphy(Grant No. 123104);supported by Natural Science Foundation of Guangxi(Grant No. 2013GXNSFAA019284);National Natural Science Foundation of China(Grant No.41162002)~~