Clam shrimp assemblage from Daohugou: A link correlating northern Hebei and western Liaoning

Abstract

The clam shrimp species, Triglypta pingquanensis Wang, 1984, is reported in the Middle Jurassic Daohugou beds from two localities in Inner Mongolia. The species is predominant in the Middle Jurassic Longmen Formation in Yingzi Village, Pingquan City, northern Hebei. This discovery significantly strengthens the correlation between the Haifanggou and Longmen formations. The clam shrimp of the Haifanggou and Longmen formations are dominated by T. haifanggouensis Chen, 1976 and T. pingquanensis, respectively. The clam shrimp assemblage from the Daohugou beds serves as a crucial link for correlating the Middle Jurassic in northern Hebei and western Liaoning, and it represents the early assemblage of the Yanliao biota. Moreover, a new species, T. hebeiensis Liao & Huang sp. nov., is described in the uppermost layer of the Longmen Formation in this study.