OBJECT OF THE MONTH - FEBRUARY 2008
Fossil Ginkgo from Siberia
Specimen of Ginkgo adiantoides from the Khutsin Formation on the Kudya River, Siberia, housed at the University of Colorado Museum of Natural History (UCM 40801). Scale is in millimeters.
Today the only living species of ginkgo, Ginkgo biloba, is native to China. But for most of their 270-million-year history, ginkgos and their relatives grew all over the world, including throughout the U.S. and UK, Asia, and Siberia.
By 65 million years ago, only one species of ginkgo occurs in the fossil record--Ginkgo adiantoides. This species had leaves almost indistinguishable from those of living G. biloba, but grew over a much broader geographic range. Many botanists consider them to be the same species.
This specimen of G. adiantoides was collected during a University of Colorado and Smithsonian Institution trip to Siberia in 1923. The trip included T.D.A. Cockerell, one of the founders of the University of Colorado Museum of Natural History.
Most of the fossil plants and insects collected in 1923 from the Khutsin Formation on the Kudya River, including the type insect specimens (representatives of new species) are in the collections of the Smithsonian Institution. Cockerell brought a small collection of plants and insects back to the University of Colorado Museum, which included this ginkgo.
Cockerell was particularly excited to work and exchange research with Russian scientists. In a letter to the journal Science written from Vladivostok in 1923, he wrote:
Altogether, we find much scientific activity, in spite of many unfavorable conditions, and every promise of important developments in a country extraordinarily rich as a field for research.
The Khutsin Formation fossils are currently thought to date to the late Eocene or early Oligocene (about 35-30 million years ago), a time of global cooling. Warmer Eocene temperatures gave way to cooler Oligocene temperatures, although the global climate was still warmer than it is today.
Today Siberia ranges from grasslands to taiga (coniferous forests). The climate is coldest in the east, where the Cockerell expedition collected fossils. During the Tertiary, when global temperatures were warmer, ginkgo, Metasequoia ("dawn redwood"), and other groups of plants that prefer temperate climates flourished widely, even in Siberia.
Cockerell and other members of the expedition also found a variety of fossil insects at the Kudya River site, which Cockerell described in a Smithsonian publication.
Siberian and other high-latitude fossil floras provide important insight into how global climate change has affected plant communities during Earth's history. Khutsin fossils like this ginkgo still hold much more information to share about our planet's past.
To Learn More
Fossil Record of the Ginkgoales
Ginkgo biloba - Its ancestors and allies
University of Colorado Museum of Natural History Object of the Month: The Primeval Ginkgo Tree
