The Extinction and Delayed Recovery of Bivalves during the Permian-Triassic Crisis

In order to reconstruct the surviva1 and recovery pattern of bivalves and probe into the reasons in the aftermath of the Permian-Triassic mass extinction, a11 available data of the Late Permian to Middle Triassic bivalve genera a11 around the world have been counted and analyzed. The bivalves be1onging to3 subclasses(Pteriomorphia, Palaeotaxodonta, and Heteroconchia) and5 lifestyles(epifaunalattached, epifauna1 motile, semi-infauna1, sha11ow infauna1, and deep infauna1) show a similar recov- ery pattern. The diversity curves of bivalves display that the recovery of bivalves was delayed to Anisian, when the genus diver- sity incrcascd ncarly to thc similar valuc of thc Changhsingian prior to thc End-Pcrmian mass cxtinction.In addition, Pcrmian survivors including1ong-term survivors, holdover species, and Lazarus taxa dominated the bivalves during the Early Triassic, but not in the Anisian(Middle Triassic). Bivalves only suffered background extinction rates during the Early Triassic, indica- ting the delayed recovery of bivalves resulted from1ong-term hostile environments.