Freshwater microconchids from the Tanzhuang Formation (Middle-Late Triassic) in North China

Abstract

We describe aggregative microconchid tubes from Middle-Late Triassic lacustrine strata of the Tanzhuang Formation in the Jiyuan-Yima Basin, North China. These microconchid tubes are attached to plant fragments and are preserved with bivalves, ostracodes, phyllostachys, gastropods, and coleoptera fragments. The findings confirm that the extinct lophophorate group inhabited non-marine continental basins. Microconchids dispersed extensively in continental basins and became common in lacustrine strata during Middle-Late Triassic. Its expansion may have been promoted by the recovery of the land ecosystem in the aftermath of the end-Permian crisis.