贵州寒武纪海绵动物化石组合特征

贵州寒武纪海绵化石丰富。分布广泛，主要产于早寒武世梅树村期的戈仲伍组或牛蹄塘组底部、筇竹寺期的牛蹄塘组和早、中寒武世凯里组。梅树村期的海绵属种单调，主要为六射海绵类麦粒海绵（Triticispongia sp．）及一些海绵骨针，代表寒武纪海绵首次爆发或辐射的前奏和先驱。牛蹄塘组海绵多达13个属，是寒武纪海绵辐射的重要窗口，以普通海绵略占优势，Leptomitus为优势属。凯里组的海绵共计7属，以普通海绵为主。贵州寒武纪海绵动物群的发展具有明显的阶段性和组成的差异性，其演变过程受到环境的制约。贵州早期海绵动物的发现和研究不仅改变了寒武纪生物多样性的认识，而且还为探讨海绵动物本身的起源、辐射提供了重要材料。

CAMBRIAN SPONGE ASSEMBLAGES FROM GUIZHOU

Cambrian sponges from Guizhou are abundant, and have been founded mostly in the lower Cambrian Gezhongwu Formation in Zhijin, the Niutitang Formation in Zunyi, Jinsha, Danzhai and lowermiddle Cambrian Kaili Formation in Taijiang. Sponge body fossil Triticispongia sp. and mass sponge spicules which first occur in Meishucunian, may be forerunners of the sponges before rapid radiation during Qiongzhusian. Sponges in the Niutitang Formation are abundant not only in numbers but also in bodyforms, 13 sponge genera constitute 70% of the whole biota, so the Niutitang Formation is a window of the first sponge radiation. These sponges are similar to that of the lower Cambrian Chengjiang biota rather than those of the Niutitang Formation at Sancha, Dayong, Hunan Province because they are mostly Demospongea, whereas in the Niutitang Formation at Sancha are primarily Hexactinellida. There are relatively few sponges in the middle Cambrian Kaili Biota, only 7 genera, and make up 6 percent of the biota. Demospongea are dominant in the Kaili biota. It is shown that the radiation of the Demospongea took place in the Qiongzhusian. Comparison of the Cambrian sponge assemblages indicates that compositions of sponge assemblages are controlled by environments. Discoveries and studies of Cambrian sponges from Guizhou provide new information for understanding early history of sponge evolution and diversity of the Cambrian marine animals.