The last phase of the end-Ordovician extinction event involved substantial sea-level changes. The Oslo/Asker District in Norway is a rare place where the deeper-water early Hirnantian fauna is succeeded by the equivalent deeper-water Edgewood-Cathay Fauna. Both faunas are highly diverse, with the same small-shelled brachiopods, and dominating. They also share a large number of long-ranging and eurytopic genera. Taxa from contemporary shallower-water environments are rare. Near a third of the brachiopod genera in the Norwegian deeper-water early Hirnantian Fauna went extinct, including seven genera that survived into the Ordovician/Silurian boundary strata. Deeper-water early Hirnatian and Edgewood-Cathay collections are not well-known worldwide. Global quantitative samples from low latitudes, including the Norwegian samples, were compared against each other using NMDS (Non-metric Multidimensional Scaling) with the Bray-Curtis index. Qualitative samples used NMDS with the Raup-Crick index and Network Analysis. The Raup-Crick index sharply differentiated the early Hirnantian and Edgewood-Cathay faunas, possibly due to sensitivity to extinction and origination data. In contrast, the paleogeographic affinity between collections of the two faunas is pronounced using the Bray-Curtis index. Network Analysis also demonstrates regionality; the Edgewood-Cathay Fauna is especially heterogeneous. This contrasts with the shallower-water Fauna, which is more cosmopolitan. Quiet waters below the storm-wave base possibly hindered the spread of larvae, and anoxic plumes of water may have caused further barriers to the lateral spreading of the Edgewood-Cathay Fauna. As in Norway, long-ranging, eurytopic taxa were shared between the two faunas with few typical shallow-water taxa.

中文翻译：

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深水、高多样性的 Edgewood-Cathay 腕足动物群及其对应的赫南蒂斯动物群

奥陶纪末灭绝事件的最后阶段涉及海平面的大幅变化。挪威的奥斯陆/阿斯克区是一个罕见的地方，这里的深水早期赫南特动物群被同等的深水埃奇伍德-华夏动物群所取代。这两个动物群都高度多样化，具有相同的小壳腕足动物，并且占主导地位。它们还共享大量的远缘属和广域属。来自当代浅水环境的类群很少见。挪威深水早期赫南特动物群中近三分之一的腕足动物属灭绝，其中包括奥陶纪/志留纪边界地层中幸存的七个属。早期的深水 Hirnatian 和 Edgewood-Cathay 系列在世界范围内并不知名。使用 NMDS（非度量多维标度）和 Bray-Curtis 指数对来自低纬度地区的全球定量样本（包括挪威样本）进行相互比较。定性样本使用 NMDS 以及 Raup-Crick 指数和网络分析。劳普-克里克指数显着地区分了早期的赫南蒂安动物群和埃奇伍德-华夏动物群，这可能是由于对灭绝和起源数据的敏感性。相比之下，使用布雷-柯蒂斯指数可以明显看出两个动物群之间的古地理亲和力。网络分析还证明了区域性；埃奇伍德-华夏动物群尤其具有异质性。这与更加国际化的浅水动物群形成鲜明对比。风暴波底部下方的安静水域可能阻碍了幼虫的扩散，而缺氧的水羽可能对埃奇伍德-华夏动物群的横向扩散造成了进一步的障碍。与挪威一样，这两个动物群共享远距离的广域类群，但典型的浅水类群很少。