''Acer alaskense'' is an extinct

maple ''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

in the family Sapindaceae described from a

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 preserved ...

leaf A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

. The species is solely known from the Latest Paleocene sediments exposed in the Matanuska River Valley,

Matanuska-Susitna Borough Matanuska-Susitna Borough (often referred to as the Mat-Su Borough) is a borough located in the U.S. state of Alaska. Its county seat is Palmer, and the largest community is the census-designated place of Knik-Fairview. The borough is part of ...

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...

. It is the type species for the extinct

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''Alaskana''.

Type locality

The species was described from a single full-leaf specimen found in the Chickaloon Formation, which underlies the Kenai Group formations. Sediments of the formation are mainly claystone through sandstone, and conglomerates with interbedded deposits of

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coal. Based on the surrounding formations and the floral composition of fossils in the formation itself, the Chickaloon dates to the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

with ''Acer alaskense'' known only from the latest Paleocene section exposed in the Even Jones coal mine.

History and classification

''Acer alaskense'' was described from a solitary

specimen Specimen may refer to: Science and technology * Sample (material), a limited quantity of something which is intended to be similar to and represent a larger amount * Biological specimen or biospecimen, an organic specimen held by a biorepository ...

, the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

(number "USNM 396009"), which is currently preserved in the paleobotanical collections housed at the

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, part of the

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Washington, D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, ...

The specimen was studied by

paleobotanist Paleobotany, which is also spelled as palaeobotany, is the branch of botany dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments (paleogeogr ...

s Jack A. Wolfe of the United States Geological Survey, Denver office and Toshimasa Tanai of

Hokkaido University , or , is a Japanese national university in Sapporo, Hokkaido. It was the fifth Imperial University in Japan, which were established to be the nation's finest institutions of higher education or research. Hokkaido University is considered ...

. Wolfe and Tanai published their 1987 type description for ''A. alaskense'' in the ''Journal of the Faculty of Science, Hokkaido University''. The

etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...

of the chosen specific name ''alaskense'' is in recognition of the type locality in the state of Alaska. ''A. alaskense'' is the oldest occurrence of the maple genus, '' Acer'', with the second-oldest being '' A. douglasense'' from the Early Eocene sediments of the Paleocene-Eocene West Foreland Formation. In their type description Wolfe and Tanai designated ''A. alaskense'' as the type and only species for the extinct ''Acer'' section ''Alaskana''.

Description

Leaves of ''Acer alaskense'' are simple in structure and generally oval in shape. The leaves are three- to possibly only two-lobed, with the fossil showing a blade with one lateral lobe. The leaf is wide and long in overall dimension. ''A. alaskense'' has a simple structure to the tertiary veins that connect the basal secondary veins, which is not seen in other species of ''Acer''. However the numerous teeth and structure of the areolar venation are very similar to the modern species '' A. spicatum''. Wolfe and Tanai note that the apparent two-lobed structure may be an aberration and ''A. alaskense'' may have typically been three-lobed.

References

{{Taxonbar, from=Q4673129 alaskense Plants described in 1987 Fossil taxa described in 1987 Paleocene plants Extinct flora of North America