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

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.