Anatomically Preserved Pteridosperm Stems and Rachises from Permian Floras of China
Anatomically Preserved Pteridosperm Stems and Rachises from Permian Floras of China
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DOI：
10.1086/599076
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发表时间：
2009-07
影响因子：
2.3
通讯作者：
L. Seyfullah;J. Hilton;Shijun Wang;J. Galtier
中科院分区：
文献类型：
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作者：
L. Seyfullah;J. Hilton;Shijun Wang;J. Galtier
蕨类植物在中国二叠纪植物群中很常见，在压着组合中既有营养器官又有可育器官，在过矿化组合中既有分散的胚珠又有种子。与此相反，从过矿化组合的营养器官的报告是有限的，在所有的情况下，帐户没有得到验证的详细描述，也没有说明。本文报道了中国二叠纪矿化植物群中的四个蕨类植物茎或轴分类群。来自Asselian-Sakmarian（Cisuralian）太原组的煤球被证明含有髓生和lyginopterid pteridosperm的标本。髓轴有一个独特的维管束侧枝组织，散布在破碎的薄壁组织中，也有分散的树脂管，它被鉴定为Myeloxylon Brongniart。长翅蕨科具有一个充满活力的原生中柱体茎，其次生木质部和中始木质部成熟，并被确认为Heterangium sp. 1。在吴家坪期-长兴期宣威组的火山凝灰岩中，一个具有薄壁髓的真柱体茎被离散的初生木质部束包围，初生木质部束具有大量次生木质部和裂头蚴型皮层，被认为是Callistophytalean Callistophyton Delevoryas和Morgan。最后，从长兴期（乐平期）王家寨组，另一个lyginopterid记录，包括一对原生中柱茎与manoxylic次生木质部和中始木质部成熟，并被分配到Heterangium sp.2。虽然这些描述是基于少量的标本数量，但它们提供了中国二叠纪植物蕨类植物属的明确证据，而这些植物以前只在宾夕法尼亚和最早的欧亚二叠纪被发现。在这种情况下，他们强调了湿地植物群落的植物区系延续，从欧美石炭纪延伸到中国北方的西苏拉纪泥炭形成沼泽和中国南方的乐平纪。扩大这些蕨类植物类群的地理和地层范围意味着，每个现在应该被认为是潜在的重要种子植物的进化和发育在二叠纪以及石炭纪。
Pteridosperms are common in the Permian floras of China and are known from both vegetative and fertile organs in adpression assemblages and as dispersed ovules and seeds in permineralized assemblages. In contrast, reports of vegetative organs from permineralized assemblages are limited, and in all cases, accounts have not been verified by detailed descriptions nor illustration. Here we report four taxa of pteridosperm stem or rachis from the Permian permineralized floras of China. Coal balls from the Asselian‐Sakmarian (Cisuralian) Taiyuan Formation are shown to contain specimens of a medullosan and a lyginopterid pteridosperm. The medullosan rachis has a distinctive collateral organization of vascular bundles interspersed within a crushed parenchymatous ground tissue that also has scattered resin ducts, and it is identified as Myeloxylon Brongniart. The lyginopterid has a vitalized protostelic stem with manoxylic secondary xylem and mesarch xylem maturation and is confirmed as Heterangium sp. 1. From volcaniclastic tuffs from the Wujiapingian‐Changhsingian (Lopingian) Xuanwei Formation, a eustelic stem with a parenchymatous pith surrounded by discrete primary xylem strands with a large amount of secondary xylem and a sparganum‐type cortex is attributed to the Callistophytalean Callistophyton Delevoryas and Morgan. Finally, from the Changhsingian (Lopingian) Wangjiazhai Formation, another lyginopterid is documented that comprises a pair of protostelic stems with manoxylic secondary xylem and mesarch xylem maturation and is assigned to Heterangium sp. 2. Although accounts are based on low specimen numbers, they provide unequivocal evidence of vegetative pteridosperm genera in the Permian of China that were previously known only from the Pennsylvanian and earliest Permian of Euramerica. In this context, they underline the floristic continuation of wetland plant communities extending from the Carboniferous of Euramerica into the Cisuralian‐aged peat‐forming mires in North China and the Lopingian of South China. Extending the geographical and stratigraphical ranges of these pteridosperm taxa means that each should now be considered as potentially important to seed plant evolution and phylogeny during the Permian as well as the Carboniferous.