First record of Pterophyllum propinquum and its epidermal structures in Yaojie Formation of Middle Jurassic in Gansu Province, Northwestern China

Abstract

ABSTRACT The leaf morphology and epidermal anatomy of a species of Pterophyllum, a morphological genus of Bennettitales, were studied in detail based on leaf fossil collected from the Middle Jurassic Yaojie Formation in the Baojishan Basin, Gansu Province, northwestern China. The fossil lamia is large; the segments are broadly linear to rectangular, opposite, each segment containing ca. 20 thin veins. The leaf cuticle is thin, hypostomatic, possessing of syndetocheilic stomatal complex. According to a detailed comparison on the basis of leaf morphology and cuticle features to other similar fossil plants, the fossil material was attributed to Pterophyllum propinquum Goeppert, which add to the details of the rachis, leaf cuticles of the species. Combined with the characteristics of paleoclimate change during the Mesozoic in China, the responses of the palaeogeographical distribution of Pterophyllum to paleoclimate change in different periods of Mesozoic in China are discussed. Moreover, based on the fossil floral assemblage and the cuticle features of P. propinquum, we presumed that it is a warm and humid climate in the Middle Jurassic in Baojishan basin, where the P. propinquum is a typical plant member.