''Metasequoia occidentalis'' is an extinct

redwood Sequoioideae, commonly referred to as redwoods, is a subfamily of Pinophyta, coniferous trees within the family (biology), family Cupressaceae, that range in the Northern Hemisphere, northern hemisphere. It includes the List of superlative tree ...

species of the family

Cupressaceae Cupressaceae or the cypress family is a family of conifers. The family includes 27–30 genera (17 monotypic), which include the junipers and redwoods, with about 130–140 species in total. They are monoecious, subdioecious or (rarely) dioecio ...

that is found as

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s throughout the Northern Hemisphere. It is one of three

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

species of ''

Metasequoia ''Metasequoia'', or dawn redwood, is a genus of fast-growing coniferous trees. It contains one extant (living) species, ''Metasequoia glyptostroboides'', which is one of three extant species of conifers known as redwoods in the world. ''Metaseq ...

'' that are currently recognized as valid.Stockey, R.A., Rothwell, G.W. and Falder, A.B. 2001. Diversity among taxodioid conifers: ''Metasequoia foxii'' sp. nov. from the Paleocene of central Alberta, Canada. International Journal of Plant Sciences, v. 162, p. 221-234.Liu, Y-J, Li, C-S, and Wang, Y-F, 1999. Studies on fossil ''Metasequoia'' from north-east China and their taxonomic implications. Botanical Journal of the Linnean Society, v. 130, p. 267-297. Metasequoia occidentalis cone 01

History

The species was first described in 1863 from fossils found in the outcrops of the Late Paleocene-Middle Eocene Chuckanut Formation around Birch Bay, Washington. The species was originally described as ''Taxodium occidentale'' by

John Strong Newberry John Strong Newberry (December 22, 1822 – December 7, 1892) was an American physician, geologist and paleontologist. He participated as a naturalist and surgeon on three expeditions to explore and survey the western United States. During the C ...

. Fossilized ''Metasequoia''-like remains were noted in Europe and North America from the 1800s on, but were assigned to the cupressaceous genera '' Sequoia'' (redwoods) and ''

Taxodium ''Taxodium'' is a genus of one to three species (depending on taxonomic opinion) of extremely flood-tolerant conifers in the cypress family, Cupressaceae. The name is derived from the Latin word ''taxus'', meaning " yew", and the Greek word ' ...

'' ( bald cypresses). It was not until the living species ''

Metasequoia glyptostroboides ''Metasequoia glyptostroboides'', the dawn redwood, is a fast-growing, endangered deciduous pinophyta, conifer. It is the sole living species of the genus ''Metasequoia'', one of three genera in the subfamily Sequoioideae of the family (botany), ...

'' was discovered and described from a remote area of China during the 1940s, that the affinity of many of the

s became apparent. In 1951, the species was reassigned to ''Metasequoia'' as ''M. occidentalis'' by

Ralph Works Chaney Ralph Works Chaney (August 24, 1890 – March 3, 1971) was an American paleobotanist. Chaney was the first paleobotanist to develop in detail the use of morphological characters of fossil leaves to deduce ecological information of the given era. ...

based on the close resemblance to living ''Metasequoia''. With a few notable exceptions, it has been claimed that the majority of the fossils documented in the literature show that ''M. occidentalis'' was indistigushable from living ''M. glyptostroboides''.

Description

Like living ''Metasequoia'', ''M. occidentalis'' was

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

. The foliage consists of branchlets with oppositely arranged leaves. The leaves are ovate to linear in shape, ranging from in length and in width, with a distinct midvein, a petiolate base, and an acute tip. The seed-bearing cones are

globose This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary ...

ovoid An oval () is a closed curve in a plane which resembles the outline of an egg. The term is not very specific, but in some areas of mathematics (projective geometry, technical drawing, etc.), it is given a more precise definition, which may inc ...

, long and wide, with decussately arranged triangular scales, and are borne on long, leafless stalks. The seeds have two wings, are ovoid to cordate in shape, and are up to long and wide. The pollen-bearing cones are small, globose to ovoid, long and wide, and oppositely arranged on specialized stalks with one terminal cone.

Age and distribution

''Metasequoia occidentalis'' appeared in fossil record during the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

epoch (

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

stage). By the

Tertiary Tertiary (from Latin, meaning 'third' or 'of the third degree/order..') may refer to: * Tertiary period, an obsolete geologic period spanning from 66 to 2.6 million years ago * Tertiary (chemistry), a term describing bonding patterns in organic ch ...

period, it had become a major constituent of lowland and swampy forests in the northern circum-Pacific and polar regions, where it commonly coexisted with '' Glyptostrobus europaeus''. Fossils assignable to ''M. occidentalis'' have been reported from parts of the United States, Canada, Russia, China, Japan, Greenland and Svalbard, but ''Metasequoia'' appears to have been rare or absent in much of Europe.LePage, B. A., Yang, H., and Matsumoto, M. 2005. The evolution and biogeographic history of Metasequoia. In: The geobiology and ecology of Metasequoia, pp. 3-114. Springer, Netherlands.

References

{{Taxonbar, from=Q21398288 occidentalis Prehistoric plants Allenby Formation Chu Chua Formation Horsefly Shales Klondike Mountain Formation Tranquille Formation Paleontology in Alberta