Ostracods in the Palaeozoic?
Ostracods in the Palaeozoic?
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DOI：
10.1007/bf03043973
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发表时间：
2008-06
期刊：
影响因子：
--
通讯作者：
D. Siveter
中科院分区：
文献类型：
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作者：
D. Siveter
在古生代地层记录中，传统上用于识别介形类产状的属性实质上是小型双壳节肢动物甲壳的存在。这些发现提供了对古生代小型双壳节肢动物软体部分古生物学的无与伦比的洞察，再加上双壳甲壳是节肢动物中的一种汇聚现象的概念，在过去的十年里，这些发现彻底改变了我们对古生代介形类主要类群的性质和地层记录的理解。来自附属物和其他软部件的证据在确定系统亲和力方面至关重要。脊椎动物和磷鳞足类软体解剖的证据破坏了寒武纪介形类的记录，但分子和化石证据表明，它们可能在当时就存在。在没有软体部分的情况下，石龙(奥陶纪-泥盆纪)是介形类的情况仍然不确定。根据大量新的古生物学证据，Myodocope肯定出现在古生代。到目前为止，所谓的古生代足底猿实际上只有化石贝壳代表。古生物群是古生代的一个主要类群，迄今被认为是一个连贯的分类群，其系统亲缘关系仍然是个谜，它们可能最终代表着一个人造类群。
The attribute traditionally used to recognise the occurrence of ostracods in the Palaeozoic stratigraphic record has in essence been the presence of a bivalved arthropod carapace of small size. Discoveries offering unparalleled insight into the soft part palaeobiology of tiny bivalved Palaeozoic arthropods, when taken together with the notion that a bivalved carapace is a convergent phenomenon within the Arthropoda, have in the last decade revolutionised our understanding of the nature and stratigraphic record of the major groups of ostracod present in the Palaeozoic. Evidence from appendages and other soft parts is crucial in determining systematic affinity. Evidence from the soft part anatomy of bradoriids and phos-phatocopids has undermined the record of ostracods in the Cambrian, but molecular and fossil evidence implies that they may be present at that time. In the absence of soft parts the case that lepetditicopids (Ordovician-Devonian) are ostracods remains uncertain. Myodocopes certainly occur in the Palaeozoic, as determined on a wealth of new palaeobiological evidence. As yet, supposed Palaeozoic podocopes are represented in practical terms only by fossil shells. The systematic affinity of palaeocopes — a major group in the Palaeozoic and hitherto recognised as a coherent taxon — remains enigmatic, and they may turn out to represent an artificial grouping.