State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.
Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Science, Beijing, China.
Nat Ecol Evol. 2018 Apr;2(4):614-622. doi: 10.1038/s41559-017-0449-3. Epub 2018 Feb 5.
Spiders (Araneae) are a hugely successful lineage with a long history. Details of their origins remain obscure, with little knowledge of their stem group and few insights into the sequence of character acquisition during spider evolution. Here, we describe Chimerarachne yingi gen. et sp. nov., a remarkable arachnid from the mid-Cretaceous (approximately 100 million years ago) Burmese amber of Myanmar, which documents a key transition stage in spider evolution. Like uraraneids, the two fossils available retain a segmented opisthosoma bearing a whip-like telson, but also preserve two traditional synapomorphies for Araneae: a male pedipalp modified for sperm transfer and well-defined spinnerets resembling those of modern mesothele spiders. This unique character combination resolves C. yingi within a clade including both Araneae and Uraraneida; however, its exact position relative to these orders is sensitive to different parameters of our phylogenetic analysis. Our new fossil most likely represents the earliest branch of the Araneae, and implies that there was a lineage of tailed spiders that presumably originated in the Palaeozoic and survived at least into the Cretaceous of Southeast Asia.
蜘蛛（Araneae）是一个具有悠久历史的非常成功的谱系。它们的起源细节仍然不清楚，对其祖群知之甚少，对蜘蛛进化过程中特征获取的顺序也几乎没有深入了解。在这里，我们描述了一种来自缅甸白垩纪中期（约 1 亿年前）缅甸琥珀的奇异蜘蛛——奇异拟幽蛛（Chimerarachne yingi gen. et sp. nov.），它记录了蜘蛛进化中的一个关键过渡阶段。与 uraraneids 一样，这两个可供研究的化石保留了分段的后体，带有鞭状的尾节，但也保留了蜘蛛目（Araneae）的两个传统的共形特征：用于精子传递的雄性触肢特化和类似于现代间蛛的明确的纺器。这种独特的特征组合将 C. yingi 确定为包括蜘蛛目和 uraraneids 在内的一个分支内的物种；然而，其相对于这些目的确切位置对我们的系统发育分析的不同参数很敏感。我们的新化石很可能代表了蜘蛛目的最早分支，这意味着可能存在一条有尾蜘蛛的谱系，它起源于古生代，并至少在东南亚的白垩纪存活下来。
