The species was described from a pair of complete fruit specimens. One of the two specimens was recovered from sediments of the early Eocene,
Ypresian The plant community preserved in the Klondike Mountain formation is a mixed confer-broad leaf forest with large pollen elements of
birch and
golden larch, but also having notable traces of
fir,
spruce,
cypress, and
palm. The Allenby formation is similar with the birch and golden larch as strong pollen signals and traces of fir and spruce, however the cypress and palm are not distinct signals.
Acer stonebergae was described from a pair of
specimens, the
holotype, number "PDMA 1984 OMC 1001" which is currently preserved in the
paleobotanical collections housed at the
Princeton District Museum and Archives and the paratype, "UWBM 56254 A,B", is in the paleobotanical collection of the Burke Museum, part of the
University of Washington in
Seattle. The specimens were studied by
paleobotanists
Jack A. Wolfe of the
United States Geological Survey, Denver office and Toshimasa Tanai of
Hokkaido University. Wolfe and Tanai published their 1987
type description for
A. stonebergae in the
Journal of the Faculty of Science, Hokkaido University. The
etymology of the chosen
specific name stonebergae is in recognition of Margaret Stoneberg from the Princeton District Museum who made the museums collections available for the authors to study.
A. stonebergae is one of three species assigned to the extinct section
Torada. The three members of the section
A. stonebergae,
A.toradense, and
A. washingtonense were known only from the Republic and Princeton fossil localities when first described. Of the three species, both
A. stonebergae and
A. toradense are only known from the samara fossils, only
A. washingtonense has been described from both leaves and samaras. The three are among a number of
Acer species described from the Republic and Princeton sites by Wolfe and Tanai. ==Description==