中国科学院南京地质古生物研究所机构知识库

Bivalves are comparatively rare elements of the benthic faunas of Jurassic and Early Cretaceous lakes of northeastern China. In the past, Arguniella and Sphaerium have been regarded as belonging to the communities that populated the offshore areas of lake Sihetun, represented by the Lower Cretaceous Yixian Formation of western Liaoning. A detailed biostratinomic analysis of these bivalves suggests, however, that they were introduced from marginal lake habitats where they were reworked by storms and occasionally were transported in suspension offshore. Some of these bivalves were dead and settled on the lake floor as single valves or articulated but opened valves (butterfly position). Others were transported alive but died on their arrival at the bottom due to inimical conditions caused by reduced oxygen levels. A similar interpretation is given for articulated valves of Ferganoconcha in thinly bedded siltstones of the Jurassic Daohugou Fossil Beds of Inner Mongolia, which were also carried alive by hyperpycnal flows to their burial site where they died due to lack of oxygen. (C) 2015 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved.