Phylogenetic and environmental context of a Tournaisian tetrapod fauna
Phylogenetic and environmental context of a Tournaisian tetrapod fauna
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DOI：
10.1038/s41559-016-0002
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发表时间：
2017-01-01
影响因子：
16.8
通讯作者：
Walsh, Stig A.
中科院分区：
文献类型：
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作者：
Clack, Jennifer A.;Bennett, Carys E.;Walsh, Stig A.
泥盆纪末到密西西比纪中期的时间间隔长期以来以其贫乏的古生物记录而闻名，尤其是四荚类。这个时期概括了四足动物陆生性增加的时期，但之前只有两个图尔奈地区出产了四足动物化石。在这里，我们描述了来自两个地点的五种新的图尔奈四足动物（Perittodus apsconditus、Koilops herma、Ossirarus kierani、Diploradus austiumensis 和 Aytonerpeton microps）的环境背景。系统发育分析检索到三个类群为茎四足动物，散布在泥盆纪和石炭纪形式之间，还有两个为茎两栖动物，表明冠四足动物之间存在深度分裂。我们还展示了来自这些地区以及苏格兰边境地区其他地区的新四足动物标本。新的分类单元和标本表明，图尔奈人已经很好地建立了四荚多样化。沉积证据表明，四足动物化石通常与湿地古土壤上的砂质粉砂岩有关。四豆荚可能生活在植被表面，随后被洪水淹没。我们表明，跨越泥盆纪/石炭纪边界的大气氧水平是稳定的，并且不会抑制陆地的演化。来自图尔奈地区的大量四豆荚凸显了在其他地方发现的潜力。
The end-Devonian to mid-Mississippian time interval has long been known for its depauperate palaeontological record, especially for tetra pods. This interval encapsulates the time of increasing terrestriality among tetrapods, but only two Tournaisian localities previously produced tetrapod fossils. Here we describe five new Tournaisian tetrapods (Perittodus apsconditus, Koilops herma, Ossirarus kierani, Diploradus austiumensis and Aytonerpeton microps) from two localities in their environmental context. A phylogenetic analysis retrieved three taxa as stem tetrapods, interspersed among Devonian and Carboniferous forms, and two as stem amphibians, suggesting a deep split among crown tetra pods. We also illustrate new tetrapod specimens from these and additional localities in the Scottish Borders region. The new taxa and specimens suggest that tetra pod diversification was well established by the Tournaisian. Sedimentary evidence indicates that the tetrapod fossils are usually associated with sandy silt stones overlying wetland palaeosols. Tetra pods were probably living on vegetated surfaces that were subsequently flooded. We show that atmospheric oxygen levels were stable across the Devonian/Carboniferous boundary, and did not inhibit the evolution of terrestriality. This wealth of tetra pods from Tournaisian localities highlights the potential for discoveries elsewhere.