Why do some paleobotanists question whether Ginkgoites should be a separate genus?

Some paleobotanists recommend abandoning the genus Ginkgoites because the significant variation in leaf form observed in fossil specimens is comparable to the range of variation found on a single living ginkgo tree (Ginkgo biloba).1

Because these fossil leaves, which date back to the Jurassic Period, exhibit similar form and venation to the living species, these researchers argue that it is more appropriate to classify them as various species within the genus Ginkgo rather than maintaining a separate, distinct genus.1