Small shelly fossils and carbon isotopes from the early Cambrian (Stages 3–4) Mural Formation of western Laurentia
Small shelly fossils and carbon isotopes from the early Cambrian (Stages 3–4) Mural Formation of western Laurentia
复制标题
DOI：
10.1002/spp2.1313
复制
发表时间：
2020-06
影响因子：
2.3
通讯作者：
C. Skovsted;U. Balthasar;J. Vinther;E. Sperling
中科院分区：
文献类型：
--
作者：
C. Skovsted;U. Balthasar;J. Vinther;E. Sperling
早、中寒武世磷酸盐化和磷酸盐化小壳化石（SSF）的异常窗口期是生物成矿后生动物辐射作用的重要证据。虽然在这段时间内，SSF在大多数寒武纪古大陆上都是众所周知的，但劳伦西亚西部的SSF动物群相对较少。本文描述了加拿大阿尔伯塔和不列颠哥伦比亚省三个地区早寒武世（第3-4期）壁画组中的多种SSF动物群，并辅以碳同位素测量，以帮助建立潜在的未来生物化学地层框架。该动物群扩大了记录的SSF组合的多样性，在西部劳伦，包括几个腕足类，四个bradoriids，三个cheororiids，两个舌骨，tommotiid和helcionellid软体动物以及棘皮动物小骨和标本的Microdictyon，Volborthella和Hyolithellus。新的分类群包括tommotiid genus pallella gen. nov.，新的bradoriid物种Hipponicharion perforata sp. nov.和Pseudobeyrichona taurata sp. nov.与来自西部Laurentia的同时代动物群相比，动物群相对多样，特别是在最初具有磷酸盐外壳的分类群中，这似乎与古杯有关。这表明，在劳伦西亚西部的动物群多样性普遍较低，可能至少在一定程度上是一个合适的archaeocyathan珊瑚礁环境采样差的结果。此外，tommotiid ellafiligrana似乎是在寒武纪第3阶段地层的劳伦西亚西部的生物地层学意义，和意想不到的高多样性的bradoriid节肢动物群也表明，这组可能被证明是有用的生物地层分辨率在该地区。
The extraordinary window of phosphatized and phosphatic small shelly fossils (SSF) during the early and middle Cambrian is an important testament to the radiation of biomineralizing metazoans. While SSF are well known from most Cambrian palaeocontinents during this time interval, western Laurentia has relatively few SSF faunas. Here we describe a diverse SSF fauna from the early Cambrian (Stages 3–4) Mural Formation at three localities in Alberta and British Columbia, Canada, complemented by carbon isotope measurements to aid in a potential future bio‐chemostratigraphic framework. The fauna expands the recorded SSF assemblage diversity in western Laurentia and includes several brachiopods, four bradoriids, three chancelloriids, two hyoliths, a tommotiid and a helcionellid mollusc as well as echinoderm ossicles and specimens of Microdictyon, Volborthella and Hyolithellus. New taxa include the tommotiid genus Canadiella gen. nov., the new bradoriid species Hipponicharion perforata sp. nov. and Pseudobeyrichona taurata sp. nov. Compared with contemporaneous faunas from western Laurentia, the fauna is relatively diverse, particularly in taxa with originally phosphatic shells, which appear to be associated with archaeocyathid build‐ups. This suggests that the generally low faunal diversity in western Laurentia may be at least partly a consequence of poor sampling of suitable archaeocyathan reef environments. In addition, the tommotiid Canadiella filigrana appears to be of biostratigraphical significance in Cambrian Stage 3 strata of western Laurentia, and the unexpected high diversity of bradoriid arthropods in the fauna also suggests that this group may prove useful for biostratigraphical resolution in the region.