''Acer alaskense'' is an extinct

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

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in the family

Sapindaceae The Sapindaceae are a family (biology), family of flowering plants in the order Sapindales known as the soapberry family. It contains 138 genera and 1,858 accepted species. Examples include Aesculus, horse chestnut, maples, ackee and lychee. The ...

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 preserve ...

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

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

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

. It is the type species for the extinct section ''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

bituminous Bitumen ( , ) is an immensely viscous constituent of petroleum. Depending on its exact composition, it can be a sticky, black liquid or an apparently solid mass that behaves as a liquid over very large time scales. In American English, the m ...

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 (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

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 f ...

, the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

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

National Museum of Natural History The National Museum of Natural History (NMNH) is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. With 4.4 ...

, part of the

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The specimen was studied by

paleobotanist Paleobotany or palaeobotany, also known as paleophytology, is the branch of botany dealing with the recovery and identification of plant fossils from geological contexts, and their use for the biological reconstruction of past environments (pale ...

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

Hokkaido University , or , is a public research university in Sapporo, Hokkaido, Japan. Founded in 1918, it is the fifth-oldest government-authorised university in Japan and one of the former Imperial Universities. The university finds its roots in Sapporo A ...

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

etymology Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. ...

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 In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

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