''Acer ivanofense'' 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 ...

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

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

aged fossils found in the

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. It is one of several extinct species placed in the living section '' Glabra''.

History and classification

''Acer ivanofense'' is represented by a group of fossil specimens recovered from late Eocene to early Oligocene outcrops of the lower Meshik Volcanics, formerly called the Meshik Formation, at

US Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, an ...

site 11418 on Road Island, Ivanof Bay on the

Alaska Peninsula The Alaska Peninsula (also called Aleut Peninsula or Aleutian Peninsula, ale, Alasxix̂; Sugpiaq: ''Aluuwiq'', ''Al'uwiq'') is a peninsula extending about to the southwest from the mainland of Alaska and ending in the Aleutian Islands. The ...

. The rocks were first named in 1929 by R.S. Knappen for material exposed along the Meshik River near Meshik Lake. In 1996 the sequence was reexamined and subsequently renamed the Meshick Volcanics by Robert L. Detterman and a group of researchers, to better reflect the

lithology The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...

of the rocks. The age of the formation is considered to range from approximately to approximately . The species is known from the holotype specimen, USNM 396017a, and three other specimens, USNM 396017b, USNM 396017c, and USNM 396017d. All four specimens are preserved in the collections of the

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. The specimens were 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 A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

for ''A. ivanofense'' 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 ''ivanofense'' is in recognition of the type location for the species in Ivanof Bay, Alaska.

Description

Leaves of ''A. ivanofense'' are simple in structure with a perfectly actinodromous vein structure in which the primary veins originate at the base of the lamina and run out towards the margin. The three-lobed leaves widely oval in shape with the lateral lobes being about one-half the width of the middle lobe. The leaves have three primary veins and an estimated size range of long by . Between four and seven secondary veins branch from the basal side of each lobal primary vein which then branch to form a bracing structure for the lobe. The leaves host compound teeth with each major tooth having two to three small teeth on the bottom edge and one tooth on the tip edge. The morphology of ''A. ivanofense'' suggests placement into the ''Acer'' section ''Glabra'' and the series ''Arguta''. This is based on the overall vein structure in the lobes and the structuring of the veins forming the areolae.

References

{{Taxonbar, from=Q4673157 ivanofense Prehistoric angiosperms Plants described in 1987 Fossil taxa described in 1987 Eocene plants Flora of Alaska Eocene species first appearances Rupelian species extinctions Extinct flora of North America