A new species of Eretmophyllum (Ginkgoales) from the Middle Jurassic of Turpan-Hami Basin, Xinjiang, China

A few specimens previously assigned to Eretmophyllum, based on the gross leaf morphology, lack cuticular structures. In this paper, we describe a new species of Eretmophyllum from the Middle Jurassic Xishanyao Formation in the Turpan-Hami Basin, Xinjiang Uygur Autonomous Region, northwestern China, based on fossil leaves preserved as compressions, and characterized by paddle shapes with conspicuous petioles, retuse apices, entire margins and two veins dichotomously branched from near the base. Leaf amphistomatic, the cuticles are composed of stomatal and non-stomatal bands. Based on a detailed comparison of the gross morphology and cuticular structures with previously reported fossils, Eretmophyllum hamiensis n. sp. is erected. The presence of Eretmophyllum indicates that Middle Jurassic climate in the Turpan-Hami Basin was likely warm and humid. On the basis of the geological history and geographical distributions of Eretmophyllum, we conclude that the genus probably originated in Europe and migrated from Siberia to northwestern China during the Middle Jurassic.