Cuticular structure of Storgaardia Harris from the Middle Jurassic of Northwest China and its systematic and biogeographical significances

Mesozoic strata are well developed in Huating County, Gansu Province, Northwest China. However, few megafossil plants from this region have been reported in detail and thus the fossil plant diversify is unclear. In this study, the new conifer species Storgaardia gansuensis n. sp. is described based on recent collections from Aalenian to Bajocian at Xihua coal mine of Huating, Gansu Province, China. The specimens are characterized by leafy shoots alternately or sub-oppositely arranged, linear to linear-lanceolate, hypostomatic leaves with thin cuticles. On the basis of the epidermal structures of St. gansuensis and comparison with extant conifers, we propose that Storgaardia is allied with Amentotaxus of Taxaceae. The paleogeographic distribution suggests that Storgaardia probably originated in the Late Triassic in East Asia, and later spread from Asia to Europe and further to East Greenland. The paleogeographic distribution of Storgaardia and associated plants indicates that they lived under a warm-temperate to temperate climate during the Middle Jurassic in East Gansu Province, Northwest China.