Multiple Fossil Ginkgo Leaf & Winged Walnut - North Dakota

This is a spectacular multiple fossil Ginkgo leaf of the species Ginkgo adiantoides, and Juglandaceae (Winged Walnut) Fruit, from the Sentinel Butte Formation of South Dakota. It is finely detailed, and the light preservation contrasts well against the dark orangish-brown rock.

During this time on the Paleocene epoch the Ginkgo genus was only represented by a single polymorphic species, Ginkgo adiantoides. This species was distributed in much of the Northern regions of North America which had a hot, humid climate. It's leaves were virtually indistinguishable from modern-day Ginkgo biloba. The species Ginkgo adiantoides went extinct approximately 7 million years ago.

The Juglandaceae (walnuts, hickories, pecans) has one of the best-documented fossil records in the Northern Hemisphere. The oldest modern genus, Cyclocarya, today restricted to China, first appears in the late Paleocene (57 ma) of North Dakota, USA. Unlike walnuts and pecans that produce edible fruits dispersed by mammals, Cyclocarya fruits are small nutlets surrounded by a prominent circular wing, and are thought to be wind- or water-dispersed. Because Cyclocarya fruits are winged, they might be assumed to be wind-disperse, but their radial symmetry does not have the aerodynamic qualities typical of wind-dispersed fruits, and may have been dispersed by water.
Ginkgo adiantoides, Juglandaceae (Winged Walnut) Fruit
Morton County, North Dakota
Sentinel Butte Formation
Largest leaf is 2.9" on 10.5x5.3" matrix
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