Monday 14 October 2013

Metasequoia Fossils

Eocene Era Metasequoia Fossil from the McAbee Fossil Beds
British Columbia
The Dawn Redwood flourished early in its evolutionary history as reflected in an extensive fossil record throughout North America and Eurasia from the early late Cretaceous to the PlioPleistocene with fossils from Western Canada, Alaska as well as the Arkala and Koylma River basins in Russia.  Possibly the Metasequoia crossed from Asia to North America across Beringia or even earlier through the Spitzbergen corridor during the early Cretaceous.  By the early Tertiary, the Metasequoia was a major component of polar broad-leaved deciduous forests.  Despite the presence of 2 land bridges linking North America and Europe throughout the early Tertiary, the Dawn Redwood did not cross into Europe 
B. A. Le Page, et al. (2005)

During the Paleocene-Eocene Thermal Maximum, extensive forests of Metasequoia occurred as far north as Axel Heiberg Island (Northern Canada)  at 80°N.  Large petrified trunks and stumps of the extinct Metasequoia occidentalis also compose the major portion of Tertiary fossil plant material in the badlands of western North Dakota in the U.S.

The pronounced decline of the Dawn Redwood is tied to increasing global aridity and cooling as well as competition for resources from the Pine family.  The bulk of metasequoia fossils show the genus has remained morphologically unchanged since the early Late Cretaceous -- a time when Angiosperms  - flowering plants - were just beginning to evolve.

Metasequoia glyptostroboides planted in late 1940s by the
pond at Kew Gardens