An exceptionally large and well-preserved drepanophycalean lycophyte specimen from the Early Emsian Hunsrück Slate exhibits branching morphology and architecture that suggest previously unrecognized diversity of drepanophycalean lycophytes in the German Early Devonian. The specimen shows long prostrate axes giving rise to both rooting axes and erect leafy, unbranched axes via K-branching. Rhizomatous growth along the substrate promoted rapid vegetative expansion of the plant forming monoclonal patches, potential adaptations to colonizing an unstable deltaic environment. K-branches including dormant buds may have allowed resurrection of the shoot system following burial by sediment or damage to growing shoot apices. Cutbank erosion may have uprooted parts of the plants, which were then transported into the open marine areas and eventually buried in the Hunsrück Slate depositional environment. We hypothesize that remains of Late Silurian/Early Devonian plants (and possibly Prototaxites) may have drifted for many kilometers and were large enough to raft small organisms over considerable distances. Thus, the Late Silurian/Early Devonian may have witnessed the earliest passive oceanic dispersal by rafting of terrestrial invertebrates and therefore marks a crucial time in Earth’s history with respect to this important paleobiogeographical factor.

中文翻译：

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表征drepanophycalean lycophytes（Lycopsida）的分支结构：来自德国西南部早期泥盆纪Hunsrück板岩的特殊标本及其古生物学意义

早于EmsianHunsrück板岩的一个非常大且保存完好的drepanophycalean苔藓植物标本显示出分支形态和结构，这表明德国早期泥盆纪的drepanophycalean苔藓植物以前是无法识别的多样性。样品显示出较长的前屈轴，通过K分支产生生根轴和直立的多叶未分支轴。沿基质的根状生长促进了植物的快速营养膨胀，形成了单克隆斑块，可能适应了不稳定的三角洲环境。包括休眠芽的K分支可能使沉积物被埋葬或破坏生长的茎尖而使茎系统复活。堤岸侵蚀可能使植物部分连根拔起，然后将其运输到开放的海洋区域，并最终埋在洪斯吕克板岩沉积环境中。我们假设晚志留纪/泥盆纪早期植物的遗存（可能还有原生陨石可能漂流了许多公里，并且足够大，可以在很长的距离上漂流小型生物。因此，志留纪晚期/泥盆纪晚期可能通过漂流陆生无脊椎动物目睹了最早的被动海洋扩散，因此就这一重要的古生物地理因素而言，标志着地球历史上的关键时期。