甘肃东部五村堡层中Zamiophyllum的发现

ON THE OCCURRENCE OF ZAMIOPYLLUM FROM THE WUTSUNPU FORMATION IN EASTERN KANSU,CHINA

本文所介绍的植物化石是一种地理分布很广、地层上的分布则只限於下白垩纪的一种标准化石。它最先发现於欧洲下白垩纪的瓦尔登期(Wealden)的地层中,后来在北美的波托马居(Potomac Formation)及日本的领石统中都有大量发现。此化石除在日本有唯一的例外,一度见於略低的手取统(上侏罗纪)外,其余各处都是出现於下白垩纪的地层中,并且一向被认为是下白垩纪瓦尔登期植物群中具有代表性的重要份子之一.此种化石过去在中国从无报道,所以此次的发现无论就它的地理分布和封於决定所在地层的时代来说,都是颇有意义的.

The monogenic plant here described was first introduced by Ettingshausenin 1852 under the name Pterophyllum buchianum from the Wealden of Germany,and subsequently it was suggested by Nathorst in 1890 aas the geno type of adistinct genus Zamiophyllum.Nathorst distinguished his new genus fromPterophyllum chiefly on that the pinnae are more oblique to the rachis andtaper gradually towards the base which is somewhat thickened.The asameplant was later described by many authors as Zamites buchianus,and Dioonitesbuchianus etc.