Oldest glosselline linguliform brachiopod with soft parts from the Lower Cambrian of Yunnan, Southern China

Lingulella chengjiangensis Jin, Huo & Wang, 1993 is one of the most abundant brachiopods from the celebrated Lower Cambrian Chengjiang Lagerstatte. A detailed study of abundant new well-preserved specimens clearly shows that their morphology and preserved soft anatomy differ widely from that of the linguliforms of the subfamily Obolinae, including Lingulella. L. chengjiangensis is herein re-described as the probable earliest member of the subfamily Glossellinae, which was previously known only from the Ordovician, and is referred to the new genus Eoglossa. Eoglossa chengjiangensis differs from species of Lingulella in lacking a dorsal pseudointerarea, having an elevated ventral proparea without flexure lines, and in the lack of pitting on the visceral areas of both valves. The detailed study of the exceptionally preserved specimens of E. chengjiangensis also reveals that it bears a unique musculature, which includes a single umbonal scar and a pair of posterolateral scars on each valve. The material of E. chengjiangensis also permits a more detailed study of the pedicle giving further insights into the early diversification and life habit of the linguliform brachiopods.