Quercus furuhjelmi
Quercus furuhjelmi was a type of 'brown (or chestnut) oak' that lived in the Paleogene period. It is only known by its fossil remains, which have been found in Kazakhstan and Alaska. According to some authorities (Trelease, 1924), they were related to the white oaks, subgenus "Lepidobalanus" (or "Leucobalanus") while others relate them to the "Heterobalanus" of East Asia. Chestnut oaks are a seemingly polyphyletic group. The chestnut oaks of East Asia (for example "Q. crispula" Blume) have been placed in the subgenus "Heterobalanus", while a chestnut oak from western North America"Q. sadleriana" R.Br.teris considered by some to  be a member of the "Leucobalanus" subgenus and by others to be in the "Heterobalanus" subgenus. Comparison of the brown leaves of the chestnut tree and the brown oaks does not indicate any fundamental distinction between the foliage of these groups, although some species of "heterobalanus" have some pointed teeth, which are absent in "Leucobalanus". Some specimens of "Q. furuhjelmi" also had some sharp teeth, which suggests that this species was probably related to "Heterobalanus".