''Acer palaeorufinerve'' 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 The Sapindaceae are a family of flowering plants in the order Sapindales known as the soapberry family. It contains 138 genera and 1858 accepted species. Examples include horse chestnut, maples, ackee and lychee. The Sapindaceae occur in tempera ...

described from series of isolated

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 ...

samaras and

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

. The species was described from

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

and is known from Korean fossils and Miocene sediments exposed in the state 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., ...

, USA. It is one of several extinct species placed in the living section '' Macrantha''.

History and classification

''Acer palaeorufinerve'' is represented by a group of fossil specimens from a number of different geologic formations. The first fossils described were recovered from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Ningyo-toge Formation in the Tomata District of Japan. Fossils have subsequently been recovered from the Late Miocene Tatsumitoge Formation in the Tomata District and the Early Miocene Ito-o Formation in the

Fukui Prefecture is a prefecture of Japan located in the Chūbu region of Honshū. Fukui Prefecture has a population of 778,943 (1 June 2017) and has a geographic area of 4,190 km2 (1,617 sq mi). Fukui Prefecture borders Ishikawa Prefecture to the north, Gi ...

. Other fossils have been included in the species from North Korea and Kamchatka, Russia. A single isolated fossil fruit possibly belonging to ''A. palaeorufinerve'' is known from North America. The specimen was recovered from the latest Early to early Middle Miocene Seldovia Point flora in the

Cook Inlet Cook Inlet ( tfn, Tikahtnu; Sugpiaq: ''Cungaaciq'') stretches from the Gulf of Alaska to Anchorage in south-central Alaska. Cook Inlet branches into the Knik Arm and Turnagain Arm at its northern end, almost surrounding Anchorage. On its sou ...

region of

Description

Leaves of ''A. palaeorufinerve'' are simple in structure with a palmate actinodromous vein structure in which the primary veins originate at the base of the lamina and run out towards the margin. The leaves range between three and five-lobed with a length to width ratio of 1:2, giving an overall pentagonal outline. The leaves have three or five primary veins, and at least one specimen is estimated to have been long by wide in overall dimensions. The samaras of ''A. palaeorufinerve'' have a nutlet which is flattened asymmetrically and a high attachment angle. The morphology of ''A. palaeorufinerve'' suggests placement into the ''Acer'' section ''Macrantha''. This is based on the overall leaf shape and long pointed shape of the lobe tips. The combination of morphological characters is noted to be most similar to leaves of the living maple species ''

Acer rufinerve ''Acer rufinerve'', the grey-budded snake-bark-maple, redvein maple or Honshū maple ( Japanese: ウリハダカエデ ''urihadakaede'', "melon-skin maple"), is a species of tree in the snakebark maple group, related to '' Acer capillipes'' (Kyus ...

'', commonly called the redvein or Honshū maple. The fossil species '' A. latahense'' from

Washington state Washington (), officially the State of Washington, is a state in the Pacific Northwest region of the Western United States. Named for George Washington—the first U.S. president—the state was formed from the western part of the Washington ...

and

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

is distinguishable from ''A. palaeorufinerve'' by the narrower medial lobe. Paleobotanists Jack A. Wolfe and Toshimasa Tanai suggest ''A latahense'' may be a descendant species of ''A. palaeorufinerve''. Acer rufinerve leaf 01 by Line1

References

{{Taxonbar, from=Q4673167 palaeorufinerve Prehistoric angiosperms Plants described in 1961 Fossil taxa described in 1961 Miocene plants Flora of Alaska Flora of Asia Extinct flora of North America