贵州寒武系杷榔组Sphen...1847的发现及古生态意义_张辉.pdf

收稿日期:2022-01-06;改回日期:2022-08-06;录用日期:2022-08-09*国家自然科学基金(41672005,42002012),贵州省科学技术厅基金(20144003,20175788,20191124)和中国科学院战略性先导科技专项(No.XDB2600000)联合资助。*通讯作者:彭进,教授。第一作者 e-mail: 古生物学报,61(4):558567(2022年12月)Acta Palaeontologica Sinica,61(4):558567(December 2022)研究论文 DOI:10.19800/ki.aps.2022002 贵州寒武系杷榔组Sphenothallus Hall,1847的发现 及古生态意义*张 辉1,2 彭 进1*王一凡1 罗绣春1 王秋军1 1 贵州大学,资源与环境工程学院,贵阳 550025;2 贵州师范学院,地理与资源学院,贵阳 550018 提要 Sphenothallus Hall,1847是刺胞动物中以细长锥管状为特征,底栖固着的一个属,始现于寒武纪并延伸至二叠纪。之前该属在贵州寒武纪的牛蹄塘生物群、剑河生物群和凯里生物群中均有报道。位于寒武纪第4阶的杷榔生物群也发现该属的化石,杷榔生物群的Sphenothallus由S.kozaki和S.kozaki?2个种组成。杷榔生物群的时代位于牛蹄塘生物群和剑河生物群之间,S.kozaki之前仅出现在捷克Jince组和中国湖北石牌组。杷榔生物群Sphenothallus的发现增加了该属在寒武纪第4期刺胞动物的多样性古生态、古地理分布及演化信息,丰富了杷榔生物群底栖固着类群的组合面貌。关键词 Sphenothallus 杷榔组 寒武系 贵州 中文引用 张辉,彭进,王一凡,罗绣春,王秋军,2022.贵州寒武系杷榔组Sphenothallus Hall,1847的发现及古生态意义.古生物学报,61(4):558567.DOI:10.19800/ki.aps.2022002 英文引用 Zhang Hui,Peng Jin,Wang Yi-fan,Luo Xiu-chun,Wang Qiu-jun,2022.Sphenothallus from the Balang Formation(Stage 4,Cambrian)of South China and its ecological implications.Acta Palaeontologica Sinica,61(4):558567.DOI:10.19800/ki.aps.2022002 Sphenothallus from the Balang Formation(Stage 4,Cambrian)of South China and its ecological implications ZHANG Hui1,2,PENG Jin1,WANG Yi-fan1,LUO Xiu-chun1,WANG Qiu-jun1 1 College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China;2 School of Geography and Resources,Guizhou Education University,Guiyang 550018,China Abstract Sphenothallus Hall,1847,a genus of benthic Cnidaria characterized by elongate cones and tubes,first oc-curred in the Cambrian and extended to the Permian.This genus has been reported from the Niutitang Formation(Stage 3,Series 2),Tsinghsutung Formation(Stage 4,Series 2),and the Kaili Formation(Wuliuan Stage,Miaolingian Series)in Guizhou Province.It has also been recently discovered in the Balang Formation(Stage 4,Series 2).Based on the characteristics of these tubular fossil specimens,two species,S.kozaki and S.kozaki?,are described from the Balang Formation.4期 张辉等:贵州寒武纪Sphenothallus Hall,1847;Zhang et al.:Sphenothallus from Cambrian,Guizhou 559 Previously,Sphenothallus kozaki was only found in the Jince Formation of the Czech Republic and the Shipai Formation of Hubei Province of South China.Compared with other species of this genus,S.kozaki possesses a long,narrow,straight,conical tube with a circular cross-section and insignificant thickening marks on the inner wall,indi-cating that the wall of S.kozaki is thin and weak.No transverse striae on the longitudinal thickening are observed.These tubes are straight throughout their length and have a very small angle of expansion.The longitudinal thickenings are not prominent in these specimens.Sphenothallus kozaki?has smaller expansion angles compared with S.kozaki,and the extension from the base to the upper carapace is approximately parallel.The specimens of S.kozaki?have mul-tiple inclined,irregular,longitudinal ridges inside,presumably resulted from taphonomic bias.We describe the holdfast morphology of Sphenothallus kozaki and S.kozaki?and analyze their attachment strategies,providing useful information on the dynamics of of substrate conditions in the Cambrian.The apices of S.kozaki and S.kozaki?specimens from the Balang Formation are conical,and the basal attachment disks are not pre-served.These characteristics suggest that the attachment strategies of these specimens are different from other gen-era.The result shows that S.kozaki and S.kozaki?rely on self-weight to insert their tips into the soft seafloor,an-choring themselves to the soft substrates.The majority of S.kozaki and S.kozaki?specimens are found in mudstone,confirming this observation.Some species of the Cambrian Sphenothallus evolved discoidal holdfast,whereas most post-Cambrian species of the genus are found with discoidal holdfast,possibly indicating that different species of the genus had different attachment strategies during the Cambrian.This change might be an adaptive response to varying substrate conditions during the Cambrian.Comparative analysis of the depositional environments indicates that both the Jince Formation and Shipai Formation are shallow-water platform facies,while the Balang Formation is a deep-water slope belt facies.The new discovery of S.kozaki in the Balang Formation suggests that this species is well adapted to different water depths and is,therefore,more widely distributed.The discovery also provides new information on the cnidarian,evolution,geographic distribution and species diversity of Sphenothallus during the Stage 4 Age(Series 2,Cambrian),and in understanding the benthic community composition of the Balang Biota.Key words Sphenothallus,Balang Formation,Cambrian,Guizhou 1 前 言 锥管形、细长管状化石在古生代地层中常见,鉴于其外部形态结构较为简单,多由有机质磷质压膜体壁和长锥形的管构成,多被归入刺胞动物。具有这种特征的化石标本软体部分多不能保存,学者多依据该类化石简单的外部形态特征进行分类,先后描述了Sphenothallus Hall,1847、Byronia Matthew,1899、Torellella Linnarsson,1871、Hyolithellus Billings,1872四属锥管状的化石类群。随着该类型化石越来越多的发现和研究方法更新,对锥管类化石详细分类和亲缘关系研