贵州西部早三叠世浅水碎屑岩相中微康奇虫(microconchids)化石的发现及其古生态意义

Discovery of Early Triassic microconchids in shallow-water clastic facies from western Guizhou Province and its palaeoecological significance

微康奇虫(microconchids)是一种主要营水生固着生活的帚形动物,在奥陶纪至侏罗纪的地层中均有广泛记录。本文报道了产自贵州遵义市播州剖面及六盘水市六枝剖面下三叠统夜郎组泥质岩中保存的微康奇虫的钙质栖管化石及印模化石。该组内的微康奇虫化石数量丰富,保存精美,电镜下可观察到其壳体特有的平行纤维薄层状微晶结构。本文共鉴定出微康奇虫化石共2科2属4种,为该门类生物在华南早三叠世浅水碎屑岩中的首次报道。古生态上,微康奇虫群落呈现出低分异度和高丰度的特征,为早三叠世恶劣海洋环境中具有较强适应能力的典型生态灾难分子。

Microconchids are a group of aquatic phoronid animals mainly in fixation lifestyle.They are widely distributed in the strata from the Ordovician to Jurassic.This study reports abundant calcareous microconchid fossils and their molds from the mudstone layers of the Lower Triassic Yelang Formation at the Bozhou section in Zunyi and the Liuzhi section in Liupanshui,Guizhou Province.These fossils are excellently preserved with unique microcrystalline structures consisting of micro-lamellar layers of parallel fibers.In this paper,a total of four species in two genera belonging to two microconchid families are identified.This is the first discovery of microconchids in the Early Triassic shallow-water clastic facies from South China.Palaeoecologically,this microconchid community shows low diversity and high abundance,typical characteristics of an ecological disaster taxon with strong adaptability to the harsh marine environment of the Early Triassic.