陕南西乡寒武纪梅树村期的马哈螺类化石

THE STUDY ON THE MAIKHANELLIDS IN THE MEISHUCUN STAGE FROM XIXIANG SOUTHERN SHAANXI PROVINCE,NW CHINA

根据陕西西乡梅树村期西乡生物群中获得的64枚马哈螺类化石个体的壳形和纹饰特征类型,确认该类化石有6个属,同时对其中3个属进行了系统分类研究,并建立了西乡中间锥新种Mediata xixiangensis sp.nov.。文中还对马哈螺类化石个体的不同部位进行了能谱分析和个体长宽高的测量统计,结果显示马哈螺类的壳质成分是磷酸钙,含少量氟和铝元素。马哈螺类的个体均较小,不超过1 mm,其中长度一般为300—700μm,宽度为250—550μm,厚度为200—300μm。上述研究对今后世界范围内寻找和研究此类化石,尤其对单板类的起源研究,有重要的意义。

Maikhanellids represent a group of the oldest monoplacophorans and they are important fossils in the Kuanchuanpu Member, Meishucun Stage. According to the individual shell shape and ornamentation types of 64 maikhanellids fossils which were collected from Xixiang Biota, Xixiang County, Shaanxi Province, NW China. we confirmed that the family Maikhanellidae consists of six genera. A new species Mediata xixiangensis sp. nov. is described in this paper. We also took EDAX analysis in different parts of those fossils and morphological measurements. The ingredients of Maikhanellids＇ shell are calcium phosphate with a small amount of fluorine and aluminum elements. Maikhanellids are small and no more than 1 mm, generally 300--700 μm long, 250--550 μm wide, and 200-- 300 μm thick. This study is of significance for the research of the Monoplacophora.