扬子地台北缘早寒武世早期的海绵骨针化石

本文详细研究了采自扬子地台北缘早寒武世早期地层中的大量海绵骨针化石。依据骨针化石的形态特征提出了海绵骨针化石的形态分类方案。总共记述了18类,28种类型。其中重点描述4个新的骨针类和11种新类型。为研究寒武纪早期海绵动物的出现、发展和演化提供了重要的实证材料。

EARLY SPONGE SPICULES OF THE EARLY CAMBRIAL ERA FROM THE NORTH MARGIN OF THE YANGTZE PLATFORM

All the sponge spicule fossile described and illustrated in this paper were collected from the Precambrian-Cambrian boundary strata in the north margin of the Yangtze platform. Other organisms associated with these spicule fossils, such as Trilobita, Ostracod, small shelly fossils and so on, are also abundant. The characteristics of these sponge spicule fossils may be summarizeed as folios: 1. Small size, commonly about 0. 5~3mm,min. 0. 2mm,Max. 12mm; 2. Various shapes,such as needle-like,nodule-like,cross-like,deerborn-like and so on; 3. Without entrance in the spicule body and undetached; 4. Smooth or rouh surface partly with small spurs; 5. Siliceous or calcaceous composition partly pyritizieds 6. Scatteredly distributed in strata and partly enriched in a spicule-bed,l~2cm. thick; 7. Rich vertical distributin in the Meishucun stage,associated with many small shelly fossils,abundant in the Qiongzhusi stage and associated with Trilobita,Brachiopoda.Brado-ricopida.Hyolitha and so on. These characteristics mentioned above show that the Porifera has already occurred in the end of Precam-brian and deve-loped to a high level in the early Cambrian. At that time,the sponge animal was the dominant sessile benthos. They may formed"soft reef"and become the centre of community ,around which some vagrant benthos moved by consisting"Biomarket". It could be imagined that the sponge and other organisms occumu-lated on the sea floor were similar to the high buildings in a great modern city. In this paper 26 types of spicule fossils.including 6 new kinds and 15 new types are illustrated.