Unusual Triassic Ginkgo Relative and Seed Fern Fossils

Description: This plaque displays a fine example of a leaf from Ginkgo-like tree with fine preservational details. This one comes from an old collection; the diused quarry is no longer accessible. This is a fine example of the preservation for which this biota is known. The Ginkgophyta probably originated about the same time as the Cycads during the late Paleozoic. The fan-shaped leaves of most members are quite distinctive. This one is atypical, with deeply dissected leaves. Indeed, it was sent to me as Ginkgo digitata, but the genus first became known in the Jurassic of Siberia. Gingko biloba is the only extant member. It is seen in association with a fine example of a seed fern known as Dicroidium, with the reverse a mass of Dicroidium leaves and fragments. Corystosperms or fork-leafed seed ferns are a group of extinct plants with mostly fern-like foliage but with real seeds found in the Southern Hemisphere lands of Gondwana. The flora of Gondwana evolved in isolation from the rest of Pangaea because of an arid desert that persisted near the equator. The seed fern Dicroidium, like Glossopteris, was found throughout Gondwana, and helped lend credence to the theory of Continental Drift. They possessed elaborate reproductive structures which had their own nomenclature. They serve as important index fossils, and some data indicate that they may have persisted into the Cretaceous when the angiosperms first made their appearance. Few are ever listed for sale—Triassic plants are rarely available, making this a desirable specimen from either side.