Permineralized Seed Plants from the Late Permian of Southern China: A New Species of Cardiocarpus
Permineralized Seed Plants from the Late Permian of Southern China: A New Species of Cardiocarpus
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DOI：
10.1086/507560
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发表时间：
2006-11
影响因子：
2.3
通讯作者：
Shijun Wang;J. Hilton;Mingmei Liang;Lil Stevens
中科院分区：
文献类型：
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作者：
Shijun Wang;J. Hilton;Mingmei Liang;Lil Stevens
报道了贵州火铺煤矿晚二叠世宣威组火山灰凝灰岩中发现的一个植物化石组合中的一种新的过矿化胚珠。胚珠大，扁平形，180°旋转对称。它有一个明显的连合，远端将珠被分成两个瓣。珠被由两部分肉种皮、也分为两部分的核种皮和在胚珠中部和顶端异常厚的内种皮组成。珠心与珠被的融合仅发生在合点处，珠心顶端很小，由近端的花粉室和远端延伸的管状突起组成。一个单一的维管束进入胚珠的基部，并在内、外种皮的边界处在主平面上分裂，形成两个珠被束，胚珠的每一侧各一个，珠心束继续延伸到珠心的基部，在那里它形成一个小的维管杯。胚珠的大体形态和血管化模式符合形态属（Morphogenus carpus Brongniart）的界限，但与先前确认的形态种（导致直立的火普树（Carpus huopuensis sp. nov.））不同。霍普新种，外肉种皮的组织很少被保存，并且在存在的情况下出现在保存不良的细胞区域的外部，这表明外肉种皮通过个体发育而剥落。尽管C. huopuensis sp. nov.是未知的，以前的证据表明这种胚珠是由针叶植物或种子蕨类植物（蕨类植物）产生的。
A new species of permineralized ovule is reported from a previously undocumented diverse fossil plant assemblage preserved in volcaniclastic tuff from the Late Permian Xuanwei Formation at the Huopu coal mine in Guizhou Province, China. The ovule is large and platyspermic, with 180° rotational symmetry. It has a pronounced commissure that distally divides the integument into two valves. The integument comprises a two‐part sarcotesta, a sclerotesta also divided into two parts, and an endotesta that is unusually thick in the central part of the ovule and at the apex. Fusion of the nucellus to the integument occurs only at the chalaza, and the nucellar apex is small, consisting of a proximal pollen chamber and a distally extending tubular projection. A single vascular bundle enters the base of the ovule and divides in the major plane at the boundary of the inner and outer sarcotesta to form two integumentary bundles, one to each side of the ovule, with the nucellar bundle continuing to the base of the nucellus, where it forms a small vascular cup. The gross morphology and the pattern of vascularization of the ovule fit the circumscription of the morphogenus Cardiocarpus Brongniart, to which the ovule is here assigned, but are distinct from previously recognized morphospecies leading to the erection of Cardiocarpus huopuensis sp. nov. In C. huopuensis sp. nov., tissues of the outer sarcotesta are rarely preserved and where present occur external to a zone of poorly preserved cells that suggests exfoliation of the outer sarcotesta through ontogeny. Although the identity and, hence, affinity of the parent plant for C. huopuensis sp. nov. are unknown, previous evidence shows ovules of this kind to be produced by either a coniferophyte or a seed fern (pteridosperm).