摘要
前言澄江海绵化石群的系统分类学、生态学、埋藏学和演化生物学等问题将分为不同专题进行研究。本文是关于澄江海绵化石的第一篇报道,研究内容侧重于细丝海绵科系统分类学。细丝海绵科属于普通海绵类,为澄江海绵群体中的优势类型,也是最为原始的普通海绵类之一。它们的骨骼甚薄,主要由席状外骨层所组成。外骨层由大小不相同的两套单轴骨针纵向排列而成;大骨针互相叠接成骨棒状或互相交错排列成网状,以便起着主要的支撑作用。
The sponges of the Lower Cambrian Chiungchussu Formation in Chengjiang, Yunnan are of unique importance in early history of sponges. At least 11 genera and 20 species have been found, forming the second most diversified metazoan group in Chengjiang. A majority of the sponges belong to the Demospongea with a broad spectrum of morphological variation and sizes. The present paper is the first report on the Chengjiang sponge fauna with its focus laid on the Leptomitidae which are a dominant group of the Demospongea, All the fossils reported in this paper were collected from Quarry M_2 on the western slope, and Quarry CF_5 on the northwestern slope of the Maotian hill, about five km SE of Chengjiang. They were embedded in the mudstone layers of the lower part of the Yuanshan Member. This member is the unit representing the upper part of the Chiungchussu Formation. Stratigraphically the fossils in our study range in a narrow interval dated as the lower Eoredlichia Zone in the trilobite sequence. Sponges have been widely accepted as an independent group of animals which are separated from Eumetazoans belonging to the Subkingdom Parazoan. They lack organized tissues and possess the potential of regeneration of the entire organism from the smallest fnagments; for these reasons their origination has been considered to be an early event in the history of animals. Their mineralized spicules would be expectedly rich in the Late Precambrian rocks in case of their early origination. However, the confirmation of this expectation has failed in fossil record. Only rare spicules have been reported from the strara of the Pre-Meishucun Stage, and part of them are still questionable.The lowest occurrence of less questionable spicules in China were described by Zhong Hua 1977 and Tang Tian-fu, Zhang Jun-ming and Jiang Xian-jian 1978 from the Late Proterozoic Doushantou Formation of lower Vendian equivalent in the Yangtze Gorges, western Hubei. Their recorded monaxons occur in the thin sections, measuring 0.1--1 mm long, and 0.01--0.02
出处
《古生物学报》
CAS
CSCD
北大核心
1989年第1期17-31,123-128,共15页
Acta Palaeontologica Sinica
