新元古代末期高家山生物群的生态多样性  

Ecological diversity in the terminal Ediacaran Gaojiashan biota

作　　者：华洪[1] 蔡耀平[1] 闵筱 柴姝 代乔坤 崔再航 HUA Hong;CAI Yaoping;MIN Xiao;CHAI Shu;DAI Qiaokun;CUI Zaihang(Shaanxi Key Laboratory of Early Life and Environments and State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an 710069,China;Chengdu Center of China Geological Survey,Chengdu 610081,China)

机构地区：[1]西北大学地质学系早期生命与环境陕西省重点实验室与大陆动力学国家重点实验室,陕西西安710069 [2]中国地质调查局成都地质调查中心,四川成都610081

出　　处：《地学前缘》2020年第6期28-46,共19页Earth Science Frontiers

基　　金：国家自然科学基金项目(41672025,41572012,41621003,41890844);中国科学院先导专项项目(XDB26000000);国家重点研发计划项目(2017YFC0603101)。

摘　　要：新元古代末期是生命演化的关键转折期,也是以微生物占主导的生态系统向显生宙以后生动物占主导的生态系统的转变期,埃迪卡拉纪大型软躯体生物以固着、底栖、食悬浮为特色,普遍缺乏运动能力。作为这一时期特殊代表的高家山生物群,是目前新元古代唯一一个以黄铁矿化三维保存的管状和锥管状化石为主导,兼有骨骼生物、原生动物、钙化蓝细菌类及遗迹化石的多门类生物组合,是研究埃迪卡拉纪末期生命演化和生态系统演变十分重要的载体。本文通过对高家山生物群古生态学的初步研究,揭示出在前寒武纪—寒武纪之交,生态系统已显示一定的多样性。为适应平底面上(level-bottom)微生物席的发育,高家山生物群的许多生物采取了适应性的生存策略,通过黏附或插入微生物席中,营底栖固着食悬浮(如Cloudina、Conotubus)或化学共生(可能的Shaanxilithes)或平躺(如Gaojiashania和Sinotubulites)食碎屑生活。底内遗迹化石表明存在可能的表栖和半内栖、可自由运动、食碎屑的造迹生物。Conotubus中常见的“回春”或“复苏”现象,Gaojiashania和Sinotubulites的身体扭转或生活姿态调整则是对频繁风暴事件的被动适应。Ediacaran fossils mark a pivotal position in the evolution of life as it transitions between the predominantly microbial ecosystems of the Precambrian and the animal ecosystems of the Phanerozoic.Ediacaran communities were dominated by sessile epibenthos and their ecological structures were relatively simple.Many modern feeding modes such as macropredation,epibiosis,and interspecific competition or mutualism were absent or poorly represented.It is generally accepted that the soft-bodied Ediacara biota is part of a "failed"evolutionary experiment and it has no clear genetic relationship with Phanerozoic organisms.However,corresponding to the evolution of typical Ediacaran soft-bodied biota,there was a great proliferation of tubular animals at the end of the late Neoproterozoic,represented by the Gaojiashan biota,where Lagersttte fossil deposit hosts a variety of soft-bodied or lightly biomineralized tubular fossils(Shaanxilithes,Gaojiashania,Sinotubulites,Conotubus,and Cloudina),calcareous microfossils(Protolagena),and calcareous cyanobacteria.Unlike other Ediacara fossil assemblages,the Gaojiashan biota is dominated by benthic sessile suspension feeders or detritus feeders.Of them,Cloudina is a millimetre-scale conical tube tapering adapically from an aperture to a rounded apex.The bulk of the tube is constructed by a series of successively stacked,repetitive,unevenly spaced,and funnel-shaped tube wall units.Cloudina occupied an epibenthic suspension-feeding life-mode,with the apex anchoring to microbially bound muddy substrate and the aperture extending upwards into the water column.Conotubus is a centimetre-sized conical tube consisting of a series of nested cylindrical-to-funnel-shaped tube walls(cylinders hereafter).This conotubular construction of nested cylinders is similar to that of the late Ediacaran fossil Cloudina.Integrated morphological,taphonomic and palaeoecological data suggest that it likely employed an epibenthic lifemode,with the apex anchoring to the muddy substrate and the aperture extendi

关 键 词：高家山生物群 新元古代末期 生态多样性 生命创新事件 微生物席底 风暴事件沉积 

分 类 号：P52[天文地球—古生物学与地层学]