A Jurassic wood providing insights into the earliest step in Ginkgo wood evolution

摘要

The fossil record of Ginkgo leaf and reproductive organs has been well dated to the Mid-Jurassic (170?Myr). However, the fossil wood record that can safely be assigned to Ginkgoales has not yet been reported from strata predating the late Early Cretaceous (ca. 100?Myr). Here, we report a new fossil wood from the Mid-Late Jurassic transition deposit (153-165?Myr) of northeastern China. The new fossil wood specimen displays several Ginkgo features, including inflated axial parenchyma and intrusive tracheid tips. Because it is only slightly younger than the oldest recorded Ginkgo reproductive organs (the Yima Formation, 170?Myr), this fossil wood very probably represents the oldest bona fide fossil Ginkgo wood and the missing ancestral form of Ginkgo wood evolution.