A new Ginkgo from the Lower Cretaceous of Liaoning, Northeast China and its evolutionary implications

A new species of Ginkgo L., G. pediculata sp. nov., is described from the Lower Cretaceous of Liaoning Province, Northeast China, on the basis of a well-preserved ovule-bearing organ. The cuticles of the integument and peduncle are generally similar to those of the lamina and petiole of the associated Ginkgoites manchurica (Yabe et Ôishi) Cao, which is among the most widely distributed Ginkgo-like leaves in the Lower Cretaceous of Northeast China. The new species is close to the Jurassic Ginkgo yimaensis Zhou et Zhang and clearly distinguished from the Paleogene species Ginkgo cranei Zhou et al. and the extant Ginkgo biloba. Although the coeval Ginkgo apodes Zheng et Zhou and G. neimengensis Xu et al. from Northeast China bear more ovules, they both have no pedicel when matured as the living species. The associated Ginkgoites-type leaves morphologically also resemble those of the Jurassic species. Therefore, Ginkgo pediculata sp. nov. appears to be closely related to the Jurassic species and is the latest representative of the group with primitive type ovulate organs and vegetative leaves so far known of Ginkgo. Since there co-exist two different types of ginkgoes, one with primitive characters (Ginkgo pediculata) and the other such as Ginkgo apodes and G. neimengensis which resemble the extent species G. biloba, the Lower Cretaceous is a critical time in the morphological evolution of the genus Ginkgo, roughly corresponding to the major global floristic transformation marked by the rapid decline of gymnosperms and drastic rise of flowering plants.