Data from: Extant primitively segmented spiders have recently diversified from an ancient lineage

Living fossils are lineages that have retained plesiomorphic traits through long time periods. It is expected that such lineages have both originated and diversified long ago. Such expectations have recently been challenged in some textbook examples of living fossils, notably in extant cycads and coelacanths. Using a phylogenetic approach, we tested the patterns of the origin and diversification of liphistiid spiders, a clade of spiders considered to be living fossils due to their retention of arachnid plesiomorphies and their exclusive grouping in Mesothelae, an ancient clade sister to all modern spiders. Facilitated by original sampling throughout their Asian range, we here provide the phylogenetic framework necessary for reconstructing liphistiid biogeographic history. All phylogenetic analyses support the monophyly of Liphistiidae and of eight genera. As the fossil evidence supports a Carboniferous Euramerican origin of Mesothelae, our dating analyses postulate a long eastward over-land dispersal towards the Asian origin of Liphistiidae during the Palaeogene (39–58 Ma). Contrary to expectations, diversification within extant liphistiid genera is relatively recent, in the Neogene and Late Palaeogene (4–24 Ma). While no over-water dispersal events are needed to explain their evolutionary history, the history of liphistiid spiders has the potential to play prominently in vicariant biogeographic studies.

活化石（living fossils）指在漫长地质时段中保留祖征的演化支。学界既往认为，此类演化支的起源与分化均发生在极早的地质时期。近年来，部分经典教科书收录的活化石类群实例对这一认知提出了挑战，其中尤以现存苏铁（cycads）与腔棘鱼（coelacanths）最为典型。
本研究采用系统发育分析方法，对地蛛科（Liphistiidae）蜘蛛的起源与分化模式展开检验。该类群因保留了蛛形纲的祖征，且仅隶属于与所有现生蜘蛛互为姊妹群的古老演化支中突蛛亚目（Mesothelae），而被视作活化石类群。依托覆盖其整个亚洲分布区的原创采样工作，本研究构建了重建地蛛科生物地理历史所需的系统发育框架。
所有系统发育分析结果均支持地蛛科及其8个属的单系性。鉴于化石证据表明中突蛛亚目于石炭纪起源于欧美地区，本研究的定年分析推测：地蛛科在古近纪（39~58 Ma）期间通过长距离陆上东向扩散，最终在亚洲完成起源。与既往认知相悖的是，现生地蛛科各属内的分化事件相对较晚，发生于新近纪与古近纪晚期（4~24 Ma）。本研究无需借助跨洋扩散事件即可解释地蛛科蜘蛛的演化历程，该类群的演化历史有望为分替生物地理学（vicariant biogeography）研究提供重要参考。