Metasequoiathe World’s most AncientTree Speies

Metasequoia(Dawn Redwood)is a fast-growing,deciduous tree,and the sole livingspecies,Metasequoia glyptostroboides,is one of three species of conifers known as redwoods.It is native to the Sichuan-Hubei region of China.山Although shortest of the redwoods,it grows to at least200 feet(60 meters)in height.Local villagers referto the original tree from which most others deriveas Shui-sa,or”water fir”,which is part of a localshrine.Since that tree’s rediscovery in 1944,the DawnRedwood has become a popular ornamental.

Together with Sequoia sempervirens(CoastRedwood)and Sequoiadendron giganteum(Giant Sequoia)of California,Metasequoia isclassified in the Cupressaceae subfamily Sequoioideae.Although Metasequoia.glyptostroboidesis the only living species in its genus,three fossil species are known as well.The otherSequoioideae and several other genera have been transferred from the former Taxodiaceaefamily to Cupressaceae based on DNA analysis.

Metasequoia redwood fossils are known from many areas in the Northern Hemisphere:more than twenty fossil species have been named(some were even identified as the genusSequoia).but are considered as just three species,M.foxii,M.milleri,and M.occidentalis(Farion2005).During the Paleocene-Eocene Thermal Maximum,extensive forests of Metasequoiaoccurred as far north as Axel Heiberg Island.(northern Canada)at around 800 N latitude.Largepetrified trunks and stumps of the extinct Metasequoia occidentalis(sometimes identified asSequoia occidentalis)also make up the major portion of Tertiary fossil plant material in thebadlands of western North Dakota in the United States.

The trees are well known from late Cretaceous to Miocene strata,but no fossils are knownafter that.Before its discovery,the taxon was believed to have become extinct during theMiocene.When it was discovered extant,it was heralded as a”living fossil”.

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