辽南复州湾太原组的燕海扇类

THE AVICULOPECTINIDS IN THE TA1YUAN FORMATION (UPPER CARBONIFEROUS) OF FUZHOUWAN, SOUTH LIAONING

本文记述了发现于辽南复州湾上石炭统太原组的燕海扇类,计5属17种。讨论了Annuliconcha与Paradoxipecten的属征及有关问题。上述发现在东北地区尚属首次。

The marine bivalves, espesially Aviculopectinids are very Abundant in the Taiyuan Formation of Fuzhouwan. 5 genera and 17 species are presented in this paper. Among they 8 species are new. This fossil assemblage is first recorded in northeast China.The diagnosis of Annuliconcha and Paradoxipecten, and the evolution of Annuliconcha are discussed in this paper. The diagnosis of Annuliconcha which proposed by Newell (1937) should be added as following: 'Radial costae are developed invariably, and spines on the external margin of coarse concentric fila are absent, weak or strong' According to a series species of Annuliconcha, the number of spines on exrornal margin of coarse concentric fila were increasing in the Carboniferous and Permian Period. In our opinion, 'the costae of first rank with numerous 'long spines, these spines project ventral margin, and extend afterward on posterior margin; the costae of second and/or third rank with short spines' may be the important diagnosis of the left valve of Paradoxipecten.