关于强壮弓笔石(Cyrtograptus robustus)的补充研究

Further studies of Cyrtograptus robustus

摘要: 在陕西紫阳新发现一块更为完整的强壮弓笔石(Cyrtograptus robustus)化石,对其始部、主枝、幼枝、胞管等特征进行了描述和数据统计,并与国内外相似的弓笔石进行对比。该种弓笔石主枝较宽,一级幼枝发育,相邻幼枝间隔胞管数为1~7个不等,随着主枝的延伸相邻幼枝间隔胞管数增大。笔石体没有二级幼枝,胞管形态为较矮的三角形。该种化石的补充研究为C. lapworthi带的弓笔石种类和弓笔石早期发育情况的研究提供了重要的基础资料。

Abstract: A complete specimen of Cyrtograptus robustus Fu, 1986 was discovered in Ziyang County of Shaanxi Province. In this paper, the specimen is described, and characteristics of main stipe, cladium and thecal of Cyrtograptus robustus are restudied. The main stipe is wider than other Cyrt. sp., and the number of thecae between successive cladium of Cy. robustus becomes larger from the proximal part to the distal end. There are more first cladiums, but with no second cladium.