A new Early Cretaceous Ginkgo ovulate organ with associated leaves from Inner Mongolia, China and its evolutionary significance

Abstract

A well-preserved Ginkgo ovulate organ and its associated leaves are described from the Early Cretaceous Huolinhe Formation of the Huolinhe Basin, Inner Mongolia Autonomous Region, China. This is the first discovery of the Ginkgo ovulate organ in the Huolinhe Basin. This ovulate organ has a cluster of (up to 6) ovules and an empty collar at the apex of a peduncle. The ovules are each seated in a collar, and five developed ovules are directly attached to the peduncle and one aborted ovule is terminated in a short pedicel. Detailed comparisons between the new Ginkgo organ and other reliable Ginkgo ovulate organs reveal that the new organ differs from any previously described organ. A new species, Ginkgo neimengensis sp. nov., is established. Leaves of Ginkgo coriacea associated with G. neimengensis are also described in detail. The close association and similarities of the cuticular structures between G. neimengensis and G. coriacea suggest that they were probably produced by the same plant. The present study further corroborates that the modern Ginkgo type ovulate organ first appeared in the Early Cretaceous and also provides new evidence for the Ginkgo evolutionary history.