辽宁本溪中三叠世苏铁类密脉中国似查米亚

Sinozamites myrioneurus(CYCADALES)FROM THE MIDDLE TRIASSIC STRATA IN BENXI,LIAONING PROVINCE

中国似查米亚属Sinozamites Sze是中国北方中、晚三叠世苏铁植物门Cycadophyta代表成分之一.自该属发现以来,该属在分类上属于苏铁目还是本内苏铁目一直不清楚.本文对产于辽宁本溪中三叠世林家组的密脉中国似查米亚S.myrioneurus表皮构造进行了研究.由于标本未保留角质层,故选择超景深显技术,发现该属气孔器属于单唇型,从而确立了该属植物属于苏铁目.研究过程中,既用盐酸又用硝酸来清除化石表面杂质.另根据已有的标本所显示的裂片和羽轴上下过渡关系,对该种羽片进行了部分重建.在此基础上,系统比较了类似的苏铁植物.

Sinozamites Sze 1956 is one of the representative genera of Cycadophyta,which includes Cycadales and Bennettitales,in the Middle and Late Triassic strata in northern China.However,the systematic position of the genus has long been unclear since it was erected.In this article,the epidermal structure of S.myrioneurus from the Middle Triassic Linjia Formation of Benxi,Liaoning,is deciphered by stereo microscope with large depth-of-field technique.Both hydrochoric and nitric acid are used to remove surface impurities for clearer images.Based on the stomatal apparatus of haplocheilic type,the genus is assigned to Cycadales.The missing part of the S.myrioneurus leaf is reconstructed according to the contextual relation of leaf segments and rachises shown on the existing specimen.At the end,the authors systematically compare fossils and extant Cycadophytes with similar names and morphologies to the genus Sinozamites.Besides the above results,this study also develops the large depth-of-field technique.With such technique,more epidermal structures of fossil plants and their systematic positions will be expectedly deciphered.