陕西岚皋地区Oktavites spiralis(螺旋奥式笔石)发育过程的初步研究

Preliminary study on the development of Oktavites spiralis in Langao area(Shaanxi Province)

Oktavites spiralis是志留纪兰多维列统特列奇阶的笔石带化石之一,具有重要的地层意义。为更精确地描述这一属种,对产自陕西岚皋地区的Cyrtograptus lapworthi笔石带的O.spiralis不同发育阶段的标本进行了详细研究,从而对其始部发育情况有了更深入的认识。同时,对O.spiralis发育过程的研究也可以成为对该属进行精确厘定的手段之一。

Oktavites spiralis is one of the most important member in the graptolite biozone of the Telychian stage （ late Llandovery, Silurian）, and is of great significance in biostratigraphy studies. To achieve a much more precise description of this species,we studied the specimens of Oktavites spiralis in different developmental stages from Cyrtograptus lapworthi zone of Langao area and got a much more understanding of the development of its proximal end. At the same time,we draw a conclusion that the phylogeny and development of 0. spiralis could also be one key to accurately defining this genus.