贵州寒武纪杷榔动物群的古生态学初探*

贵州剑河辣子寨村辣子寨剖面杷榔组的杷榔动物群是近期发现的一个化石丰度较大的产地。目前已发现了海绵动物、刺细胞动物、曳鳃动物、腕足动物、软舌螺动物、节肢动物、棘皮动物、藻类等8大类群的化石代表,计有63属80种。本文依据辣子寨剖面杷榔化石库下化石层的生物组合及各类群的生态特性、埋藏特征,探讨杷榔动物群的生态系及生活环境。杷榔动物群的生物群落,包括了底栖固着、内栖钻孔、表栖游移、漂游和游泳的生物类群,且生物群生活在赤道地区以北开阔海盆的透光区至弱透光区、水域含氧、海底有氧—弱氧、盐分正常、快速沉积事件频发的陆棚较深水环境。其古生态特点为:生物种类丰富,具有滤食、食草、食泥、食肉和食腐的动物;而捕食-被捕食的食物网的关系较为复杂,具有明显的金字塔型的营养结构。

PRELIMINARY STUDY ON PALEOECOLOGICAL CHARACTERISTICS OF BALANG FAUNA(STAGE 4,CAMBRIAN)IN JIANHE,EASTERN GUIZHOU PROVINCE,CHINA

The Lazizhai section of the Balang Formatiom near Lazhizhai village,Jianhe,Guizhou,China is the most prolific locality of the Balang Fauna.Body fossil remains from this locality have been recognized in at least eight major groups of organisms, including sponges, chancelloriids,cnidarians, "worms", brachiopods, hyoliths,arthropods,echinoderms and"algae",a total of 63 genera and 80 species.Here,based on the fossil assemblage from the Lower Fossil Bed of the Laizizhai section of the Balang Formation(Cambrian Stage 4)and their paleoecological groups and taphonomic groups and sedimentary characters,the ecosystem of the Balang Fauna is recognized.Its ecological groups include the benthic,nektonbenthic and nektonic to planktonic organisms.The characters of ecological groups and sedimentary evidences of the Lower Fossil Bed suggest that the Balang Fauna lived in an open sea basin north of the equator,where a deep shelf of rapid depositional event often developed.It is a biotope to have oxygenated and normal salinity,and photic environment,but,to be an aerobic to dysaerobic on the seabed.The ecosystem of the Balang Fauna includes carnivores(predators and scavengers), deposit-feeders and filter-feeders.Analysis of the predator-prey systems reveals a complex food web with a trophic structure containing several trophic levels, with obvious pyramidal nutritional structure.