Three Indeterminate Forms of Scalidophoran Worms from the Cambrian Fortunian of South China

A wide variety of scalidophoran worms have been found in the Cambrian Fortunian in recent years,suggesting that scalidophorans diversified during this age.Here,we report new scalidophoran material obtained from the 2nd member of the Kuanchuanpu Formation(Fortunian Stage)in Zhangjiagou Lagerst?tte,Xixiang County,Shaanxi Province,South China.Three indeterminate forms of scalidophoran worms are described in detail.The morphology of these worms differs from that of any coeval worms and may represent new taxa.However,because these fossils are fragmented and lack detailed information on the arrangement pattern of introvert scalids,they are named here in open nomenclature.This study enriches the diversity of the earliest scalidophorans to 7 genera and species and 10 indeterminate forms.Based on the new fossils,Fortunian scalidophoran worms can be divided into three categories:(1)worms with microannuli;(2)worms with macroannuli;and(3)worms without annuli.

寒武纪初期宽川铺生物群Eopriapulites sphinx的蜕皮行为

陕南寒武纪幸运期宽川铺生物群已经报道了多种生物化石,如藻类、基础动物、两侧对称动物和许多分类位置不定的化石,它是探索早期动物门类起源和寒武纪生命大爆发的重要窗口。该生物群中的Eopriapulites sphinx是目前已知最早的蜕皮类蠕虫(有吻突动物),但至今尚未发现能反映其蜕皮行为的证据。本文通过对E.sphinx新标本的外部形态和内部结构进行扫描电镜和Micro-CT研究,发现了处于蜕皮阶段和蜕皮后阶段的标本,并构建出E.sphinx完整的蜕皮过程,即经历了蜕皮前、蜕皮时和蜕皮后三个阶段。E.sphinx的蜕皮特征与同时代具刺状骨片的有吻突动物和现生鳃曳动物的蜕皮行为一致。该发现为研究寒武纪初期有吻突动物的蜕皮过程提供了新思路。