Abstract Four Dicroidium species and associated fertile organs are here described from the late Permian Umm Irna Formation (Dead Sea Region, Jordan). Dicroidium irnense, D. jordanense and D. robustum, which were so far only known from the Wadi Himara locality, are now reported from several other sites, some yielding nearly complete fronds and excellently preserved cuticles; D. hughesii, a species so far only known from the Triassic, is here reported from the upper Permian. The largest species, D. robustum emend. nov., can be correlated with the pollen organ Pteruchus lepidus sp. nov. and the cupulate structure Umkomasia aequatorialis sp. nov. based on repeated co-occurrences and striking similarities in cuticular features. Dicroidium irnense is associated with Pteruchus frenguellii sp. nov. based on consistent co-occurrence. Dispersed Umkomasia seeds are common in all localities where Dicroidium occurs. The here described material comprises some of the most completely reconstructed species of Umkomasiaceae known to date. All Dicroidium plants are characterized by comparatively large fronds and both Pteruchus species have strongly elongate, strap-shaped microsporophylls, similar to Triassic Umkomasiaceae growing under comparable, seasonally dry conditions. Dicroidium first appeared during the late Permian in the paleotropical regions, survived the end-Permian biotic crisis, colonized large parts of Gondwana during the Triassic, and persisted in southern high-latitude refugia into the Jurassic. Umkomasiaceae thus show a remarkable resilience as the group survived two of the most severe mass extinctions in Earth history.

中文翻译：

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对约旦二叠纪Dicroidium植物（Umkomasiaceae）全株重建的贡献

摘要 本文描述了晚二叠纪 Umm Irna 组（约旦死海地区）的四种 Dicroidium 物种和相关的可育器官。Dicroidium irnense、D. jordanense 和 D.robustum 迄今为止仅在 Wadi Himara 地区已知，现在在其他几个地点也有报道，其中一些产生了几乎完整的叶状体和保存完好的角质层；D.hughei 是迄今为止仅在三叠纪发现的物种，在此报告自二叠纪上层。最大的种类，D.robustum emend。nov., 可以与花粉器官 Pteruchus lepidus sp. 相关联。十一月 和杯状结构 Umkomasia aequatorialis sp。十一月 基于表皮特征的重复共现和惊人的相似性。Dicroidium irnense 与 Pteruchus frenguellii sp 相关。十一月 基于一致的共现。分散的 Umkomasia 种子在所有 Dicroidium 发生的地方都很常见。这里描述的材料包括一些迄今为止已知的最完整的 Umkomasiaceae 重建物种。所有 Dicroidium 植物都具有相对较大的叶状体，并且两种 Pteruchus 物种都具有强烈拉长的带状小孢子叶，类似于在可比较的季节性干燥条件下生长的三叠纪 Umkomasiaceae。Dicroidium 最早出现在二叠纪晚期的古热带地区，在二叠纪末的生物危机中幸存下来，在三叠纪期间殖民了冈瓦纳大陆的大部分地区，并在南部高纬度避难所持续到侏罗纪。Umkomasiaceae 因此表现出非凡的复原力，因为该群体在地球历史上两次最严重的大规模灭绝中幸存下来。