摘要
寒武纪早期陕南宽川铺生物群和湖北岩家河生物群盛产次生磷酸盐化的小壳化石,其中包含了大量刺胞动物化石,这为研究刺胞动物起源和演化提供了绝佳的窗口。寒武纪幸运期四方塔形壳属Quadrapyrgites和第二期八叶塔形壳属Octapyrgites形态相似,如四辐射对称、易变形的围鞘表面发育近平行的不规则的褶皱。在相邻时期已知的刺胞动物化石中,二者之间形态特征最为接近,由于缺乏过渡环节的化石标本,它们之间的亲缘关系尚需进一步验证。本文报道了寒武纪幸运期陕南宽川铺生物群新型八叶塔形壳属化石:Octapyrgites denticulus sp.nov.(檐牙八叶塔形壳),其典型特征在于具8个口折叶和更加低矮的反口锥部。该新种与宽川铺组Q.quadratacris总体轮廓相似,区别在于口折叶的数目不同,后者具12个口折叶。虽然Octapyrgitesdenticulussp.nov.在陕南宽川铺组张家沟剖面数量少,但在湖北岩家河组亦有发现,因此并非Q.quadratacris的种内变异类型。新种与湖北岩家河生物群寒武纪第二期的Octapyrgites elongatus在体形、基部大小、基部纵纹等方面有别,但均具8个口折叶,表明二者亲缘关系最为接近,很可能具有最晚的共同祖先。从寒武纪幸运期四方塔形壳属Quadrapyrgites到第二期八叶塔形壳属Octapyrgites形态差异逐渐扩大;形态上Octapyrgitesdenticulussp. nov.很可能代表了Q. quadratacris与O. elongatus之间的中间过渡类型。
The Early Cambrian Kuanchuapu biota in southern Shaanxi and Yanjiahe biota in Hubei are rich in secondarily phosphatized small shelly fossils, including diverse microscopic sedentary medusozoans, which provide excellent window for investigating the origin and evolution of the cnidarians. In comparison with co-occurred medusozoans, Quadrapyrgites quadratacris of Kuanchuanpu biota and Octapyrgites elongatus of Yanjiahe biota are very similar to each other in periderms, such as the tetraradial symmetry, irregular longitudinal folds nearly paralleling to the oral-apical axis of plastic, and pagoda-like shape. However, whether they represent either an intraspecific variation distinct taxa or not, needs to be further clarified. We describe here Octapyrgites denticulus sp. nov., a new tower-shaped microscopic, sedentary medusozoans from the Kuanchuanpu biota(the Cambrian Fortunian Stage) in southern Shaanxi.The excellent three-dimensional, secondary phosphatized microfossils allowed us to compare their morphology with the very similar form from the first small shell fossil zone of the Yanjiahe biota(the Lower Cambrian Stage 2) in Hubei province in details. Although shared with the same tetraradial symmetry, O. denticulus sp. nov. differs from the cooccurring Q. quadratacris in eight apertural lobes. O. denticulus sp. nov. differs O. elongatus from their body size, the apical longitudinal striations, and the size of apical zone, but both of them exhibit eight apertural lobes that may suggest a closer affinity. O. denticulus sp. nov., morphologically, may represent an intermediate form between O. elongatus and Q. quadratacris in the basal Cambrian.
作者
雍媛媛
彭佳欣
王星
鱼驰洋
郝文静
孙洁
郭俊锋
韩健
YONG Yuanyuan;PENG Jiaxin;WANG Xing;YU Chiyang;HAO Wenjing;SUN Jie;GUO Junfeng;HAN Jian(Shaanxi Key Laboratory of Early Life and Environments and State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,P.R.China;School of Earth Science and Resources,Key Laboratory of Western China's Mineral Resources and Geological Engineering,Ministry of Education,Chang'an University,Xi'an 710054,P.R.China;College of Life Science,Linyi University,Linyi 276000,P.R.China)
出处
《微体古生物学报》
CSCD
北大核心
2022年第3期223-234,共12页
Acta Micropalaeontologica Sinica
基金
中国科学院战略性先导科技专项(B类)资助项目(XDB26000000)
国家自然科学基金项目(41672009,41621003,41772010,41720104002,42172016)资助。
关键词
八叶塔形壳属
宽川铺生物群
幸运期
寒武纪
陕南
Octapyrgites
Kuanchuanpu biota
Fortunian stage
Cambrian
southern Shaanxi
