山东潍坊寒武系苗岭统乌溜阶馒头组上部的腕足动物

寒武系腕足动物属种多样性高、个体数量丰富、形态差异明显、地理分布广泛,具有辅助寒武系三叶虫生物地层划分和对比的潜力。华北板块寒武系苗岭统沉积和化石记录发育良好,是中国苗岭统的经典研究区之一。前人已针对华北寒武系苗岭统乌溜阶腕足动物的系统古生物学开展了一系列基础工作,但这些相关研究主要集中于辽宁地区,目前对华北其他地区苗岭统乌溜阶腕足动物的研究程度仍然有限,相关生物地层学也有待进一步探索。本文首次系统描述了山东潍坊寒武系苗岭统乌溜阶馒头组上部碎屑岩中的腕足动物,共鉴定出舌形贝型亚门4属5种,包括馒头组洪河段的舌孔贝未定种Lingulellotreta sp.indet.以及馒头组上页岩段的山西小舌形贝Lingulella shansiensia(Walcott,1905)、德姆斯小舌形贝Lingulella damesi (Walcott,1905)、伊瑞克乳房贝Acrothele eryx (Walcott,1905)和东方原孔贝Prototreta orientalis(Resser and Endo,1937)。值得注意的是,在馒头组上页岩段的3层岩性略有差异的泥岩中,分布着3层完全不同的腕足动物,共有4种,但这3个组合都位于Bailiella lantenoisi带这一三叶虫生物带。腕足动物组合在极短时间内的快速交替现象,表明了腕足动物对环境背景的微弱变化具有较强的响应。

Brachiopods from the upper part of the Mantou Formation (Cambrian, Miaolingian, Wuliuan) in Weifang, Shandong, North China

The Cambrian brachiopods had high species diversity, remarkable individual abundance, considerable morphological varia-tion and wide geographical distribution, showing the potential in assisting the Cambrian biostratigraphic subdivision and correlation based on trilobites. The North China plate possesses well-developed sedimentary and fossil records of the Cam-brian Miaolingian and has been one of the classic research areas of the Miaolingian in China. A series of previous works have been done on the systematic palaeontology of Cambrian Miaolingian Wuliuan brachiopods from North China. However, these relevant studies were mainly concentrated within the Liaoning area. The current research on the Cambrian Miaolingian Wuliuan brachiopods in other parts of North China is limited, and the related biostratigraphy also needs further exploration. In this paper, we systematically describe for the first time the brachiopods from the clastic rocks of the upper part of the Mantou Formation (Cambrian, Miaolingian, Wuliuan) in Weifang, Shandong. A total of four genera and five species of the subphylum Linguliformea were identified, including Lingulellotreta sp. indet. from the Honghe Member of the Mantou Formation, as well as Lingulella shansiensis (Walcott, 1905), Lingulella damesi (Walcott, 1905), Acrothele eryx (Walcott, 1905) and Prototreta orientalis (Resser and Endo, 1937) from the Upper Shale Member of the Mantou Formation. It is worth noting that there are four brachiopods species in three layers of slightly lithologically different mudstones in the Upper Shale Member of the Mantou Formation, but all the three assemblages fall within the Bailiella lantenoisi Zone, which is a single trilobite biozone. The rapid alternation of brachiopod assemblages in a very short period indicates that brachiopods might have a strong response to weak changes in environmental background.