内蒙古早三叠世的Scalaroxylon及其演化意义  

EARLY TRIASSIC SCALAROXYLON IN NEI MONGOL AND ITS EVOLUTIONARY SIGNIFICANCE

作　　者：张武[1] 李楠[2] 杨小菊[3] 王永栋[3] 傅小平[2] 李勇[2] 郑少林[1] 

机构地区：[1]沈阳地质矿产研究所,沈阳110032 [2]深圳市仙湖植物园,广东深圳518004 [3]中国科学院南京地质古生物研究所,南京210008

出　　处：《古生物学报》2006年第3期332-344,共13页Acta Palaeontologica Sinica

基　　金：深圳市科技局资助;深圳仙湖植物园资助;国家自然科学基金(No.40472004和No.40572010)部分资助课题。

摘　　要：描述产于内蒙古下三叠统老龙头组木化石梯纹木属的一个新种ScalaroxylonjalaidqienseZhangetZhengsp.nov.及一个新联合种S.multiforium(ZhengetZhang)ZhangetZhengcomb.nov.。Scalaroxylon原产于德国上三叠统考依波层,当前报道的产自内蒙古的新材料是该类型化石在中国的首次发现。该属以次生木质部为代表,生长轮不存在,它的主要特征是管胞径向壁纹孔全为梯纹纹孔;木射线1至多列,异形;射线细胞的水平壁无孔,端壁通常具孔,弦向壁多数具孔。根据次生木质部管胞的纹孔类型和木射线构造特征对该属在植物系统演化上的意义进行了初步探讨,认为它代表了种子蕨类到苏铁类之间的中间环节。Two new taxa ascribed to Scalaroxylon ）alaid- qiense Zhang et Zheng sp. nov. and S. multiforium （Zheng et Zhang） Zhang et Zheng comb. nov. were described in this paper from the Lower Triassic Laolongtou Formation of Defatun district, Jalaid Qi, Nei Mon＂ gol, China. The genus Scalaroxylon was found originally from the Upper Triassic （Keuper） of Franconia, Southern Germany. The new material documented represents the first record of this fossil wood genus in China. This genus is characterized by the secondary xylem with no growth rings. The pittings on radial walls of tracheids are of primitive scalariform type. The xylem rays are of a heterogeneous type. Both vertical and transverse ray cells are present. The horizontal and end walls of the ray cells have occasional pits, while their tangential walls are mostly pitted. This kind of special structure suggests that the genus Scalaroxylon differs from Bennettitales and primitive angiosperms, but resembles some Late Paleozoic Pteridospermae （e. g. Medullosa）and living Cycadales （e. g. some species of Zamia）. Thus, the Scalaroxylon may represent an intermediate form between the Pteridospermae and Cycadales.

关 键 词：Scalaroxylon 演化意义 早三叠世 内蒙古 

分 类 号：Q914[天文地球—古生物学与地层学]