陕南镇巴筇竹寺期的海绵骨针化石

在陕南镇巴下寒武统西蒿坪段和水井沱组下段的碳酸盐地层中含有大量保存完好、类型多样的海绵骨针化石。基于形态描述法,对海绵骨针化石进行了详细的形态描述及产地与层位判断。结果表明：根据与其共生的小壳化石和三叶虫等生物地层学资料,发现这些海绵骨针化石属于筇竹寺期;该区海绵骨针类型不仅包含有形态规则的二轴四射骨针、三轴六射骨针、三轴五射骨针,而且还有形态不规则的四轴四射骨针、五轴五射骨针、尖头星状骨针、二歧分叉式骨针等;其中的四轴四射骨针、五轴五射骨针、五刺尖头星状骨针、二歧分叉二射式骨针为本次发现的新类型,极大地丰富了海绵骨针的类型。陕南镇巴筇竹寺期海绵骨针化石的数量以及分异度快速增加,充分说明海绵动物在陕南地区寒武纪早期开始大量繁盛并且迅速演化。

Sponge Spicule Fossils of Qiongzhusian Age in Zhenba County of Southern Shaanxi Province

Sponge spicule fossils are abundant and diverse from carbonatite strata in Xihaoping Member and the lower Shuijingtuo Formation of Lower Cambrian at Zhenba County of southern Shaanxi Province. Based on morphology method, the sponge spicule fossils were described in detail, and the habitat and location of stratum were shown. The results showed that the sponge spicule fossils were in Qiongzhusian Age according to the biostratigraphy data including small shelly fossil and trilobite which were symbiotic with the sponge spicule fossils; there were tetractines, hexactines and triaxon pentactines which were regular, and there were tetraron tetractines, pentaxon pentactines, oxaster and dichostauractines which were irregular; the tetraron tetractines, pentaxon pentactines, oxaster pentaxon and dichobixactines were the new types. Quantity and disparity of Sponge spicule fossils increased fast during Qiongzhusian Age at Zhenba County of southern Shaanxi Province, so that sponges began to propagate and evolve rapidly during Early Cambrian.