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A giant Ordovician anomalocaridid

机译：巨大的奥陶纪异常异常

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Anomalocaridids, giant lightly sclerotized invertebrate predators, occur in a number of exceptionally preserved early and middle Cambrian (542-501 million years ago) biotas and have come to symbolize the unfamiliar morphologies displayed by stem organisms in faunas of the Burgess Shale type. They are characterized by a pair of anterior, segmented appendages, a circlet of plates around the mouth, and an elongate segmented trunk lacking true tergites with a pair of flexible lateral lobes per segment. Disarticulated body parts, such as the anterior appendages and oral circlet, had been assigned to a range of taxonomic groups-but the discovery of complete specimens from the middle Cambrian Burgess Shale showed that these disparate elements all belong to a single kind of animal3. Phylogenetic analyses support a position of anomalocaridids in the arthropod stem, as a sister group to the euarthropods. The anomalocaridids were the largest animals in Cambrian communities. The youngest unequivocal examples occur in the middle Cambrian Marium Formation of Utah but an arthropod retaining some anomalocaridid characteristics is present in the Devonian of Germany. Here we report the post-Cambrian occurrence of anomalocaridids, from the Early Ordovician (488-472 million years ago) Fezouata Biota in southeastern Morocco, including specimens larger than any in Cambrian biotas. These giant animals were an important element of some marine communities for about 30 million years longer than previously realized. The Moroccan specimens confirm the presence of a dorsal array of flexible blades attached to a transverse rachis on the trunk segments; these blades probably functioned as gills.
机译：异常轻蜥蜴是巨大的轻度硬化的无脊椎动物，存在于许多特别保存的早寒武纪和中寒武纪（542-501百万年前）的生物区系中，并且已经象征着伯吉斯页岩型动物群中茎生物表现出的陌生形态。它们的特征是一对前部分段的附肢，嘴周围的一圈小圆盘和一个细长的分段的躯干，缺少真实的尾部，每节有一对灵活的侧裂。分离的身体部位（例如前肢和口腔小环）已分配到一系列分类学组中，但是从中寒武纪伯吉斯页岩中发现的完整标本表明，这些不同的元素都属于一种动物3。系统发育分析支持节肢动物茎中异常节肢动物的位置，作为节肢动物的姐妹群体。异常动物是寒武纪社区中最大的动物。最年轻的明确例子出现在犹他州的中寒武统玛里姆地层中，但是在德国泥盆纪存在一种节肢动物，保留了一些异常定位特征。在这里，我们报道了摩洛哥东南部奥陶纪早期（488-472百万年前）费索阿塔生物群发生的寒武纪异常现象，其中包括比寒武纪生物群更大的标本。这些巨兽是某些海洋群落的重要组成部分，比以前意识到的要长大约三千万年。摩洛哥标本证实在躯干节段的横向轴上附着有一系列柔性叶片的背侧。这些叶片可能充当g。

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  • 来源
    《Nature》 |2011年第7348期|p.510-513|共4页
  • 作者

    Peter Van Roy; Derek E. G. Briggs;

  • 作者单位

    Department of Geology and Geophysics, Yale University, PO Box 208109, New Haven, Connecticut 06520, USA,Research Unit Palaeontology, Department of Geology and Soil Science, Ghent University,Krijgslaan 281/S8, B-9000 Ghent, Belgium;

    Department of Geology and Geophysics, Yale University, PO Box 208109, New Haven, Connecticut 06520, USA,Yale Peabody Museum of Natural History, Yale University, New Haven, Connecticut 06520, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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