Schools of Earth Sciences and Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
Natural History Museum of Denmark, Copenhagen University, Universitetsparken 15, 2100 , Denmark.
Nature. 2014 Mar 27;507(7493):496-9. doi: 10.1038/nature13010.
Large, actively swimming suspension feeders evolved several times in Earth's history, arising independently from groups as diverse as sharks, rays and stem teleost fishes, and in mysticete whales. However, animals occupying this niche have not been identified from the early Palaeozoic era. Anomalocarids, a group of stem arthropods that were the largest nektonic animals of the Cambrian and Ordovician periods, are generally thought to have been apex predators. Here we describe new material from Tamisiocaris borealis, an anomalocarid from the Early Cambrian (Series 2) Sirius Passet Fauna of North Greenland, and propose that its frontal appendage is specialized for suspension feeding. The appendage bears long, slender and equally spaced ventral spines furnished with dense rows of long and fine auxiliary spines. This suggests that T. borealis was a microphagous suspension feeder, using its appendages for sweep-net capture of food items down to 0.5 mm, within the size range of mesozooplankton such as copepods. Our observations demonstrate that large, nektonic suspension feeders first evolved during the Cambrian explosion, as part of an adaptive radiation of anomalocarids. The presence of nektonic suspension feeders in the Early Cambrian, together with evidence for a diverse pelagic community containing phytoplankton and mesozooplankton, indicate the existence of a complex pelagic ecosystem supported by high primary productivity and nutrient flux. Cambrian pelagic ecosystems seem to have been more modern than previously believed.
大型、活跃的悬浮滤食动物在地球历史上多次进化，独立于鲨鱼、鳐鱼和硬骨鱼等不同群体，以及须鲸中出现。然而，从早古生代开始，这个生态位的动物就没有被发现过。异足类动物是一种生活在寒武纪和奥陶纪时期的节肢动物，通常被认为是顶级掠食者，是最大的洄游动物。在这里，我们描述了来自格陵兰北 Sirius Passet 早寒武世（第 2 阶）的异足类动物 Tamisiocaris borealis 的新材料，并提出其前附肢是专门用于悬浮滤食的。该附肢具有长而细、间距相等的腹侧刺，上面有密集的长而细的辅助刺。这表明 T. borealis 是一种微食性悬浮滤食者，它使用附肢进行网兜式捕捉，可捕捉到 0.5 毫米以下的食物颗粒，食物颗粒的大小范围与桡足类等浮游动物相似。我们的观察表明，大型、洄游悬浮滤食动物最早是在寒武纪大爆发期间进化的，这是异足类动物适应性辐射的一部分。早寒武世出现洄游悬浮滤食动物，以及含有浮游植物和浮游动物的多样化浮游群落的证据，表明存在一个由高初级生产力和营养物质通量支撑的复杂浮游生态系统。寒武纪浮游生态系统似乎比以前认为的更加现代。
