甘肃酒西盆地早白垩世两种Elatides化石微细构造

现已绝灭的古老松柏类植物似纵属Elatides在中生代北半球中高纬度植被组成研究上具有重要意义。甘肃酒西盆地早白垩世地层中发现了Elatides的营养枝和雌球果，并保存有较好的碳膜，对它们进行了详细的宏观形态和微细特征研究。根据营养枝、叶角质层、花粉、球果、苞鳞和种子的特征，鉴定这些化石为2个种：Elatides harrisii Chow和Elatides curvifolia (Dunker) Nathorst。其中：Elatides harrisii的突出特征是，花粉球形且具乳状小突起、表面光滑无纹饰，侧面观具褶皱；Elatides Curvifolia的显著特点为，着生于苞鳞腹面基部的种鳞先端三裂，具三枚胚珠。这些特征与现生杉木Cunninghamia非常相似，推论Elatides与现生Cunninghamia可能具有亲缘关系。通过对Elatides地质历史和地理分布的研究，发现该属的演化方向与中生代大陆漂移的方向具可比性，因而为板块构造学说提供了又一古生物学佐证。

Microstructure of Two Species of Elatides Fossils from the Early Cretaceous in the Western Jiuquan Basin, Gansu Province

As an ancient conifer, Elatides is of great significance for studying the composition of high-latitude vegetation in Northern Hemisphere during the Mesozoic Era. Some vegetative shoots and female cones of Elatides fossils with carbonaceous membrane were collected from the Lower Cretaceous, Jiuquan basin. Their gross morphology and well preserved features have been studied in detail. According to the features of vegetative shoots, leaf cuticular, pollen grains, female cones, cone scales and seeds, these fossils were identified as two species: Elatides harrisii Chow and Elatides curvifolia (Dunker) Nathorst. The prominent features of E. harrisii are spherical pollen grains, possessed small emulsion protrusions and smooth surface without ornamentation, being of longitudinal furrow in lateral view. The significant characteristics of E. curvifolia are their seed scale born in the base of ventral of cone scale and its tip Trifid with three ovules. These features are much similar to those of the extant Cunninghamia. It can be inferred that there may be a genetic relationship between Elatides and Cunninghamia. By researching the geological history and geographical distribution of Elatides, it is much comparable between the evolutional of the genus and the direction of the continental drift in Mesozoic, thus it can provide some paleontological evidence to the plate tectonics theory.