The highlands, including the Eocene formations between Driftwood canyon and Republic, have been described as one of the "Great Canadian Lagerstätten"[3] based on the diversity, quality and unique nature of the paleofloral and paleofaunal biotas that are preserved.

The highlands temperate biome preserved across a large transect of lakes recorded many of the earliest appearances of modern genera, while also documenting the last stands of ancient lines.

[3] The warm temperate highland floras in association with downfaulted lacustrine basins and active volcanism are noted to have no exact modern equivalents.

[4] Fossils of Ulmus chuchuanus were first reported and briefly described by Edward W. Berry (1926) from outcrops of the Chu Chua Formation near Josephs Creek in south-central British Columbia.

[5] However Berry's name was still a resulting homonym, which wasn't rectified until the current name, Ulmus chuchuanus was coined by Robert LaMotte in 1952 based on the name of Penhallow's original specimens.

[6][2] Robyn Burnham (1986), in her review of the western United States Eocene Ulmaceae fossil record identified a fruit and three distinct leaf morphotypes at Republic.

[7] The next year Jack Wolfe and Wesley Wehr published their monograph on the Republic flora dicots, in which they listed "Ulmus species and "new genus aff.