Silicified cupulate seed-bearing structures from the Early Cretaceous of eastern Inner Mongolia, China: rethinking the corystosperm concept
Silicified cupulate seed-bearing structures from the Early Cretaceous of eastern Inner Mongolia, China: rethinking the corystosperm concept
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DOI：
10.1080/14772019.2022.2133644
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发表时间：
2022-11
影响因子：
2.6
通讯作者：
G. Shi;Fabiany Herrera;P. Herendeen;E. G. Clark;P. Crane
中科院分区：
文献类型：
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作者：
G. Shi;Fabiany Herrera;P. Herendeen;E. G. Clark;P. Crane
该类群被非正式地称为壳子植物，最初是根据冈瓦纳三叠纪的压缩化石进行描述的，长期以来一直被认为是了解种子植物系统发育、种子植物繁殖结构的进化和被子植物关系的关键灭绝植物。在这里，我们描述了一个带有种子结构的壳子植物新属和新种，Jarudia zhoui gen。等11月，基于从中国东北部内蒙古东部早白垩世霍林河组新发现的燧石中收集到的丰富硅化物质。 Jarudia zhoui 是一种松散的种子锥，由带有落叶、螺旋排列、侧向种子轴承单元的柔性中心轴组成。单独的种子承载单位由部分融合到不分枝的杯斗柄上的细长苞片组成，其顶端具有单个反折的杯斗。每个杯罩由强烈反折的杯罩柄和一个正中瓣和两个侧瓣组成。由两个维管束和三个无维管化瓣提供的壳斗柄部分包围两个三角种子。 Jarudia Zhoui 与加拿大早白垩世的 Doylea tetrahedrasperma 以及蒙古早白垩世的类似植物有着惊人的相似之处。在单个杯盖的结构和解剖学、它们的轴向性质以及具有两个分支的整个种子结构的结构方面，与冈瓦纳三叠纪的乌姆科马西亚的排卵结构也有很强的相似性。来自Jarudia zhongi的新信息，加上来自北半球的其他壳子植物排卵器官的信息，显着扩展了我们对这一关键灭绝植物群的理解，表明早白垩世和三叠纪的壳子植物的杯斗是同源的，并提出了关于壳子的定义和系统发育限制的关键问题，包括早白垩世和三叠纪如何壳子植物彼此相关，并与其他种子植物类群（包括被子植物）相关。
The group referred to informally as the corystosperms, described initially based on compression fossils from the Triassic of Gondwana, have long been considered critical extinct plants for understanding seed plant phylogeny, the evolution of seed plant reproductive structures and the relationships of angiosperms. Here we describe a new genus and species of corystosperm seed-bearing structure, Jarudia zhoui gen. et sp. nov., based on abundant silicified material collected from the newly discovered chert in the Early Cretaceous Huolinhe Formation of eastern Inner Mongolia, north-eastern China. Jarudia zhoui is a lax seed cone consisting of a flexible central axis bearing deciduous, helically arranged, lateral seed-bearing units. Individual seed-bearing units consist of an elongate bract partially fused to an unbranched cupule stalk that bears a single, reflexed cupule apically. Each cupule is formed by the strongly reflexed cupule stalk and one median and two lateral flaps. The cupule stalk supplied by two vascular bundles and three unvascularized flaps partially enclose two three-angled seeds. Jarudia zhoui bears a striking resemblance to Doylea tetrahedrasperma from the Early Cretaceous of Canada and similar plants from the Early Cretaceous of Mongolia. There are also strong similarities with ovulate structures of Umkomasia from the Triassic of Gondwana in the structure and anatomy of individual cupules, their axial nature, and the architecture of the entire seed-bearing structure that has two orders of branching. New information from Jarudia zhoui, together with information on other corystosperm ovulate organs from the Northern Hemisphere, significantly expands our understanding of this key group of extinct plants, suggests that the cupules of the Early Cretaceous and Triassic corystosperms are homologous, and raises critical questions about the definition and phylogenetic circumscription of the corystosperms, including how Early Cretaceous and Triassic corystosperms are related to each other and to other groups of seed plants, including angiosperms.