A structurally preserved cycad-like stem, Lioxylon liaoningense gen. et. sp nov., from the Middle Jurassic in Western Liaoning, China
A structurally preserved cycad-like stem, Lioxylon liaoningense gen. et. sp nov., from the Middle Jurassic in Western Liaoning, China
复制标题
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Zhang Wu;Wang Yongdong;K. Saiki;L. Nan;Zheng Shaolin
中科院分区：
文献类型：
--
作者：
Zhang Wu;Wang Yongdong;K. Saiki;L. Nan;Zheng Shaolin
摘要根据辽西侏罗纪构造保存的材料，描述了一种类似苏铁的化石-Lioxylon liaoningense gen.et sp. nov.。该标本由7个矿化岩柱组成，产于辽宁省北票市长皋镇中侏罗统髻山组。茎长，圆柱形至梨形。茎的顶端被螺旋状排列的叶柄和芽苞叶基部组成的盔甲覆盖。髓和皮层较大，由髓束粘液囊、薄壁组织、输注细胞和鞘细胞组成。它们被两圈木质部圆柱体所包围，内圈是向心的，外圈是离心的。叶柄和芽叶基部的维管束由两个束系组成，一个束系沿着叶柄和芽叶基部的近轴边缘呈弧形排列，另一个束系由中心向远轴边缘呈不发达的Ω形或不规则形。
Abstract A cycad-like fossil stem, Lioxylon liaoningense gen. et sp. nov. is described based on structurally preserved material from the Jurassic in western Liaoning, China. The specimens consist of seven permineralized stems and occur from the Middle Jurassic Tiaojishan Formation in Changgao Town, Beipiao City, Liaoning Province. The stems are long and cylindrical to pyriform in shape. The apical part of the stem is covered with an armor composed of helically arranged petioles and cataphyll bases. The pith and cortex are large, consisting of medullary bundles' mucilage sacs, parenchyma, transfusion and sclerotic cells. They are surrounded by two rings of xylem cylinders, the inner one centripetal and the outer centrifugal. The vascular bundles in the petiole and cataphyll base consist of a two bundle series; one is arranged in an are along the adaxial margin of the petiole and the cataphyll bases, and the other one is a poorly-developed omega or irregular shape and extends from the center to the abaxial ...