PERMIAN-TRIASSIC HISTORY OF REEFAL THALAMID SPONGES: EVOLUTION AND EXTINCTION

All described Permian Triassic reefal thalamid sponges are checked under the same taxonomic standard of species and those incorrectly assigned are placed respectively in the right taxon. Then the thalamid sponges of different Permian Triassic periods are compared at specific level in this study. The division of Permian System by Jin et al. (1997) (Table 1) and that of Triassic System by Harland et al . (1989) (Table 2) are followed. All described thalamid sponges from Permian and Triassic reefs are included in the study, except for those without pictures, which makes it impossible for us to check their identification. Pictures of all described thalamid sponges used in the study have been compared to the picture of the monotype of a given species and those inappropriately identified by previous researchers were assigned to the right taxon. In previous studies medium size (diameter > 0.5 cm) and large size (diameter >1 cm) thalamid sponges caught more attention. On the contrary, small thalamid sponges were mostly overlooked. In this study small thalamid sponges in the Changhsingian reefs of Ziyun, Guizhou Province, China are also included.

Project Supported:

Clc Number:

Q915.812.1