What is "sphenobaiera"

Sphenobaiera is a plant that lived in the Late Cretaceous period. The genus Sphenobaiera is used for plants with wedge-shaped leaves that can be distinguished from Ginkgo, Ginkgoites and Baiera by the lack of a petiole. It became extinct about . The family to which this genus belongs has not been conclusively established; an affinity with the Karkeniaceae has been suggested on morphological grounds.