Ordovician geography and faunal provinces deduced from trilobite distribution
Ordovician geography and faunal provinces deduced from trilobite distribution
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DOI：
10.1098/rstb.1972.0001
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发表时间：
1972-01
期刊：
影响因子：
--
通讯作者：
H. B. Whittington;C. Hughes
中科院分区：
文献类型：
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作者：
H. B. Whittington;C. Hughes
根据世界各地的资料，编制了奥陶纪地层系列中三叶虫科属名录。这些动物群之间的差异已评估在属和家庭的水平，使用辛普森指数。这些指数已通过非度量多维缩放技术进行分析，所揭示的分组被解释为指示动物区系省份。下奥陶统中有四个省，其中三个省（Bathyurid省、Asaphid省和Selenopeltis省）的动物群特征和地理范围如前所述。第四个省，这里命名为Asaphopsis省，被认为是南美洲和澳大利亚的动物群在Arenig和Llanvirn;来自东南亚的动物群的亲缘关系是不确定的。在卡拉多克，来自于Bathyurid、Asaphid和Asaphopsis动物群的动物群，以及来自于东南亚的三叶虫，构成了一个单独的省，在这里被命名为Remopleuridid。Selenopeltis省存在于南欧和北非。这两个省只能通过阿什吉尔的属分析来识别，而该系列的最新动物群是世界性的。据推测，一个动物区系最初延伸到一个单一大陆块的部分地区（参见。威尔逊1966年），各省之间的迁移受到海洋宽度或温度差异的抑制。与这些假设相一致的大陆块组合，并与古地磁数据，提出了四个奥陶纪时期的古地理图。威尔逊（1966）和麦克希尼和勒克（1970）提出的冈瓦纳大陆的位置被接受;欧亚大陆的其余部分被划分为四个块体。这些地图表明，各大陆块之间的相对运动可能消除了移徙的障碍，并导致动物区系的逐步合并。这些模型将被用来检验其他动物群的分布、新的古地磁和古气候证据以及岩石圈板块理论。地理重建表明，南美洲、南欧和北非的动物群生活在冷沃茨，北美洲、北方、东北亚、东南亚和澳大利亚的动物群生活在暖沃茨。较冷水域的动物群似乎没有那么多样化。奥陶纪期间动物区系区域性的减少似乎伴随着总多样性的减少;假定的气候恶化似乎并没有导致多样性的增加。Bathyurid和Remopleuridid省内同时代动物群之间的差异进行了研究，并反映了在这些环境中发生的三叶虫群体的环境和演变和多样化的差异。
Lists of families and genera of trilobites from the stratigraphical series of the Ordovician have been compiled, using information considered adequate from various areas in the world. Dissimilarities between these faunas have been assessed at both generic and family level, using Simpson's index. These indices have been analysed by a non-metric multidimensional scaling technique, and the groupings revealed are interpreted as indicating faunal provinces. Four provinces are recognized in the Lower Ordovician, the faunal characteristics and geographical extent of three of them (the Bathyurid, Asaphid and Selenopeltis provinces) being as previously described. A fourth province, here named the Asaphopsis province, is proposed for South American and Australian faunas in the Arenig and Llanvirn; the affinities of faunas from southeast Asia are indeterminate. In the Caradoc, faunas from areas occupied earlier by Bathyurid, Asaphid and Asaphopsis faunas, together with trilobites from south-east Asia, constitute a single province, here named the Remopleuridid. The Selenopeltis province persists in southern Europe and North Africa. These two provinces are recognizable only by a generic analysis in the Ashgill, and the latest faunas of that series are world-wide. It is assumed that a faunal province originally extended over parts of a single continental mass (cf. Wilson 1966), and that migration between provinces is inhibited by width of seas or temperature differences. An assemblage of continental masses consistent with these assumptions, and with palaeomagnetic data, is proposed to give four palaeogeographical maps for the Ordovician period. The position of the proto-Atlantic ocean proposed by Wilson (1966), and Gondwanaland of McElhinney & Luck (1970), are accepted; the remainder of Eurasia is divided into four blocks. The maps suggest relative movements between continental blocks that may have removed barriers to migration and resulted in progressive merging of the faunal provinces. They are models to be tested against distributions of other animal groups, new palaeomagnetic and palaeoclimatic evidence, and theories on lithosphere plates. The geographical reconstructions imply that the faunas of South America, southern Europe and North Africa inhabited cool waters, those of North America, northern Europe, north-east Asia, south-east Asia and Australia, warm waters. Cooler water faunas appear to have been less diverse. Decreasing provinciality of faunas during the Ordovician appears to have been accompanied by a reduction in total diversity; supposed climatic deterioration does not seem to have resulted in increased diversity. The differences between contemporaneous faunas within the Bathyurid and Remopleuridid provinces are investigated, and are shown to reflect differences in environment and evolution and diversification of groups of trilobites which took place in these environments.