A Dwarf Euomphalid Fauna from the Permian-Triassic Boundary in Laolongdong, Beibei, Chongqing: Opportunity Taxa Surviving the Disaster Event?
重庆北碚老龙洞二叠－三叠系界线层中的全脐螺侏儒化: 环境突变中的机会群落?

This paper has reported for the first time an euomphalid microgastropod fauna from the Permian-Triassic boundary section at Laolongdong, Chongqing. The euomphalids are characterized by planispiral or trochiform shell, obvious umbilicus, and calcite composition of the shell. The euomphalid fauna flourished for a short period after the mass extinction, and its blooming might have been related to the resuming of aerobic environments after an anoxic period. However, in the following time, the abundance of euomphalids kept low and failed to play an important role in the recovery of gastropods in the Early Triassic.