陕西宁强地区早寒武世磷酸盐化Punctatus新材料

描记在陕西南部宽川铺地区的灯影组宽川铺段的震旦-寒武系界线附近发现的具五辐对称特征磷酸盐化Punctatus新种———Punctatus triangulicostalissp.nov.(三角隆脊瘤点壳)。新种的锥体由5条放射状排列的锥脊组成,柱体由5纵列等间隔排列的三角隆脊组成,构成了完美的五辐对称生物体。同时描记的有PunctatusemeiensisHe,1980,新种与它的显著区别是具有与锥顶5条放射脊相对应的5纵列三角隆脊。新种呈三维立体保存,暗示生物体内部已具有一定的硬化程度,而锥体表层及柱状体表面的三角隆脊为磷酸盐化软组织。形态功能分析表明,Punctatus在分类上可能更接近于腔肠动物的水螅型。

NEW MATERIAL OF PHOSPHATIZED PUNCTATUS FROM LOWER CAMBRIAN IN NINGQIANG, SOUTH SHAANXI, CHINA

Punctatus triangulicostalis sp. nov., is found from the Kuanchuanpu Member of the Dengying Formation near the Sinian-Cambrian boundary of Ningqiang County, Shaanxi Province. It is a kind of rare and perfect five-radial-conelike metazoan. It differs from Punctatus emeiensis in having five lines composed of triangle-like transverse ridges that correspond to the pattern of a five-radial-symmetric organisim. The new species,three-dimensionally preserved in the rock layers implies that the organism has the ability to produce the skeleton representing an important innovation of the coelenterate trying to create hardparts since the extinction of the soft-bodied Ediacara fauna. Perhaps it represents an ancestor of the coelenterata with hardparts.