New fossil material of <i>Equicalastrobus</i> (Equisetales) and associated leaves from the Late Triassic of Baojishan basin, Gansu Province, China

A new species of <i>Equicalastrobus pusillus</i> L. Zhang et D.F. Yan sp. nov. and associated leaves <i>Schizoneura koningensis</i> were reported from the Late Triassic of Baojishan basin, Gansu Province, China. Cones found here were spicate, with peltate discs surrounding the axis, and the leaf-like umbo projections were identifiably smaller in size compared to the type species. Sporangiophores showed a loose arrangement implying the cones had been expanded before they were buried. Associated leaves were attributed to <i>Schizoneura koningensis</i>, due to their characteristic features. In order to discuss the relationship of fertile genus <i>Equicalastrobus</i> with other Equisetales cones, a clustering analysis on characters of reproductive organs covering 46 equisetalean cones (14 extant and 32 extinct) was performed. The character matrix was based on 36 discrete characters and 6 continuous characters. According to the clustering result, it was suggested that the new species, as well as the genus <i>Equicalastrobus</i> had a closer relationship with <i>Equisetum</i>-type cones, rather than <i>Calamites</i>-type cones. The co-occurrence of the two genera, <i>Equicalastrobus</i> and <i>Schizoneura</i>, demonstrated a wide distribution of equisetaleans with a rich and diverse morphology around the Triassic World.中国甘肃省宝积山盆地晚三叠世地层中，报道了一新种——小形等球果（Equicalastrobus pusillus）L. Zhang et D.F. Yan sp. nov.，以及其伴生叶片康氏裂鞘叶（Schizoneura koningensis）。本次发现的孢子叶球呈穗状结构，其盾状盘环绕着孢子叶球轴，叶状脐状突起的尺寸显著小于该属的模式种。孢子囊柄排列较为疏松，暗示该孢子叶球在被埋藏前已处于舒展状态。伴生叶片因具有典型形态特征，被归属于康氏裂鞘叶（Schizoneura koningensis）。为探讨可育属等球果属（Equicalastrobus）与其他木贼目（Equisetales）孢子叶球的亲缘关系，研究人员针对涵盖46个木贼目孢子叶球（其中14个为现生类群、32个为绝灭类群）的繁殖器官性状开展了聚类分析。该分析所用的性状矩阵基于36个离散性状与6个连续性状构建。根据聚类分析结果，该新种与等球果属（Equicalastrobus）均与木贼属（Equisetum）型孢子叶球具有更近的亲缘关系，而非芦木属（Calamites）型孢子叶球。等球果属（Equicalastrobus）与裂鞘叶属（Schizoneura）两个类群的伴生共存，表明木贼目（Equisetales）类群在三叠纪时期全球分布广泛，且形态丰富多样。

搜集汇总

背景与挑战

背景概述

该数据集报道了晚三叠世甘肃宝积山盆地的新化石材料，包括新物种Equicalastrobus pusillus sp. nov.和伴生叶片Schizoneura koningensis，并通过聚类分析表明Equicalastrobus属与Equisetum型球果关系更近，而非Calamites型球果，揭示了晚三叠世木贼类植物的广泛分布和形态多样性。