A revised Cretaceous age for ammonites, originally identified as Middle Jurassic, eastern Heilongjiang, China

Recent studies by Liang Zhongfa and Wang Yigang on the Qihulin Formation. Longzhaogou Group. eastern Heilongjiang Province of China indicated the presence of marine Middle Jurassic strata based on ammonite determinations. The original identifications were of a phylloceratid oxyceritid, kosmoceratid and cardioceratid. These determinations are critically re-assessed here and are now believed to comprise mainly desmocerataceans with subordinate tetragonitids. The Qihulin Formation is therefore of Cretaceous age with potential ages from Barremian to Maastrichtian, but it cannot be resolved further here because of the poor ammonite preservation . This revised age has implications for the regional biostratigraphy and the lithostratigraphy and in particular for the independent dating of the coal-bearing measures of the Longzhaogou and Jixi groups. No evidence remains for Middle Jurassic strata in eastern Heilongjiang.