放射虫新属Gansuceratoikiscum化石保存模式和基本构造功能分析

FOSSIL PRESERVATION MODES AND FUNCTIONAL DISCUSSION OF THE BASIC STRUCTURES OF A NEW RADIOLARIAN GENUS GANSUCERATOIKISCUM WANG GEN. NOV.

描述一放射虫新属种Gansuceratoikiscum guanzhuangensis Wang,产于甘肃平凉市附近官庄剖面平凉组底部钙质泥岩中,伴生的牙形类化石属于Pygodus anserinus带,时代被确定为晚奥陶世早期桑比期。讨论放射虫化石的三种保存模式,它们分别代表壳体的幼年、成熟和衰亡三个时期。讨论在角舍虫科中,仅仅根据穴肋对的有无及其数目来建立新种的这一标准的可疑性。最后,对新属种主要骨骼基本构造功能进行初步分析。

A new radiolarian genus Gansuceratoikiscum found in the lime mudstone in the basal part of the Pingliang Formation at the Guanzhuang section near Pingliang City,Gansu Province,is described. The conodont fossils associated with this new genus belong to the Pygodus anserinus zone which is regarded as early Late Ordovician Sandbian in age. The three preserved modes of the radiolarian fossils may represent three different life stages of the animals：from young,adult to aged stage,which can be used for distinguishing new species in the family Ceratoikiscidae are distinguished only by the possession,absence and the numbers of the paired caveal ribs is doubled. Last,the functions of the basic structure of the new genus Gansuceratoikiscum are briefly discussed.