State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China;
Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, China.
Proc Natl Acad Sci U S A. 2021 Mar 16;118(11). doi: 10.1073/pnas.2013442118. Epub 2021 Mar 8.
Noeggerathiales are enigmatic plants that existed during Carboniferous and Permian times, ∼323 to 252 Mya. Although their morphology, diversity, and distribution are well known, their systematic affinity remained enigmatic because their anatomy was unknown. Here, we report from a 298-My-old volcanic ash deposit, an in situ, complete, anatomically preserved noeggerathialean. The plant resolves the group's affinity and places it in a key evolutionary position within the seed plant sister group. sp. nov. is a small tree producing gymnospermous wood with a crown of pinnate, compound megaphyllous leaves and fertile shoots each with Ω-shaped vascular bundles. The heterosporous (containing both microspores and megaspores), bisporangiate fertile shoots appear cylindrical and cone-like, but their bilateral vasculature demonstrates that they are complex, three-dimensional sporophylls, representing leaf homologs that are unique to Noeggerathiales. The combination of heterospory and gymnospermous wood confirms that , and thus the Noeggerathiales, are progymnosperms. Progymnosperms constitute the seed plant stem group, and extends their range 60 My, to the end of the Permian. Cladistic analysis resolves the position of the Noeggerathiales as the most derived members of a heterosporous progymnosperm clade that are the seed plant sister group, altering our understanding of the relationships within the seed plant stem lineage and the transition from pteridophytic spore-based reproduction to the seed. Permian Noeggerathiales show that the heterosporous progymnosperm sister group to seed plants diversified alongside the primary radiation of seed plants for ∼110 My, independently evolving sophisticated cone-like fertile organs from modified leaves.
栉羊齿目植物是神秘的植物，存在于石炭纪和二叠纪时期，约 3.23 亿至 2.52 亿年前。尽管它们的形态、多样性和分布情况广为人知，但由于其解剖结构未知，它们的系统亲缘关系仍然扑朔迷离。在这里，我们从一个 2.98 亿年前的火山灰沉积物中，报道了一个原位、完整、解剖上保存完好的栉羊齿目植物。该植物确定了该类群的亲缘关系，并将其置于种子植物姐妹群的关键进化位置。 sp. nov. 是一棵小树，产生裸子植物木质部，具有羽状、复叶的冠层和每根带有 Ω 形维管束的可育枝。异孢的（含有小孢子和大孢子）、双孢子囊可育枝呈圆柱形和圆锥形，但它们的双侧脉管系统表明它们是复杂的、三维的孢子叶，代表了独特的栉羊齿目植物的叶子同源物。异孢子和裸子植物木质部的结合证实了 ，以及栉羊齿目植物，是原裸子植物。原裸子植物构成了种子植物的主干群， 将其范围扩展到 6000 万年，直至二叠纪末期。分支分析确定栉羊齿目植物的位置是异孢原裸子植物分支的最衍生成员，是种子植物的姐妹群，改变了我们对种子植物主干谱系内的关系以及从蕨类植物孢子为基础的繁殖向种子的转变的理解。二叠纪栉羊齿目植物表明，与种子植物共同进化的异孢原裸子植物姐妹群，在大约 1.1 亿年的时间里与种子植物的主要辐射一起多样化，从改良的叶子中独立进化出复杂的锥形可育器官。
