加拿大卑诗省的伯吉斯页岩以含有各种各样软体动物化石而出名，这些动物来自寒武纪中期，距今约5.1亿年前，它们提供了一个了解早期海洋动物的窗口。现在，人们知道类似的动物来自相距非常远的不同地方，如中国和格陵兰，但过去有关证据似乎表明，这些动物在寒武纪中期灭绝了。实际上不是这样的。
一种“伯吉斯页岩型”动物群落已在摩洛哥的Lower Fezouata 和Upper Fezouata构造中发现，其时间在距今约4.80亿-4.72亿年前的早奥陶世。 这种类型的动物在寒武纪之后显然还存在，之所以这样，既与软体化石保存机会有关，也同样与灭绝和存活有关。Fezouata生物区系为伯吉斯页岩群落和“奥陶系大规模生物多样化事件”（海洋生命史中最大事件之一，以前几乎全部由有壳类动物化石来代表）的早期阶段提供了一个联系。
本期Nature封面所示为来自Fezouata生物区系的一种marrellomorph节肢动物（很可能是Furca sp.）。（生物谷Bioon.com）
生物谷推荐原文出处：
Nature doi:10.1038/nature09038
Ordovician faunas of Burgess Shale type
Peter Van Roy,Patrick J. Orr,Joseph P. Botting,Lucy A. Muir,Jakob Vinther,Bertrand Lefebvre,Khadija el Hariri& Derek E. G. Briggs
The renowned soft-bodied faunas of the Cambrian period, which include the Burgess Shale, disappear from the fossil record in the late Middle Cambrian, after which the Palaeozoic fauna1 dominates. The disappearance of faunas of Burgess Shale type curtails the stratigraphic record of a number of iconic Cambrian taxa. One possible explanation for this loss is a major extinction2, 3, but more probably it reflects the absence of preservation of similar soft-bodied faunas in later periods4. Here we report the discovery of numerous diverse soft-bodied assemblages in the Lower and Upper Fezouata Formations (Lower Ordovician) of Morocco, which include a range of remarkable stem-group morphologies normally considered characteristic of the Cambrian. It is clear that biotas of Burgess Shale type persisted after the Cambrian and are preserved where suitable facies occur. The Fezouata biota provides a link between the Burgess Shale communities and the early stages of the Great Ordovician Biodiversification Event.
