Lower Devonian brachiopods from East Ujimqin Banner, Inner Mongolia, and their paleobiogeographic significance

A total of 12 genera and 16 species of brachiopods from the Lower Member of the Niqiuhe Formation in the East Ujimqin Banner region of Inner Mongolia are described herein. Based on the composition of the brachiopod assemblage, the age of the Lower Member of the Niqiuhe Formation is proposed as Emsian of the Early Devonian. Based on a dataset of the Emsian brachiopod genera from northern China and other typical fossil localities worldwide, this study applies multiple analytical methods to investigate the brachiopod paleobiogeography of this period. The results indicate that the Junggar Basin, northern Inner Mongolia, and the northern and eastern parts of Heilongjiang shared close paleobiogeographic affinities during the Emsian, belonging to the Balkhash-Okhotsk Province of the Old World Realm. Furthermore, they exhibited stronger biogeographic connections with the northwestern margin of Laurentia than with the Paleo-Tethys Ocean domain.