The McAbee flora of British Columbia and its relation to the Early-Middle Eocene Okanagan Highlands flora of the Pacific Northwest

Abstract

Megafossils and pollen data are used to compare the flora found at the McAbee site, located near the town of Cache Creek, British Columbia, to six other well-collected Eocene lacustrine floras of Washington and western British Columbia. A diverse flora is found at McAbee consisting of at least 87 taxa. Gymnosperms are common, including sixteen separate species, 14 conifers and two ginkgos. A minimum of 67 angiosperm genera are represented in the flora, many yet to be described. The dominant dicotyledonous elements of the leaf assemblage at McAbee include Fagus (also represented by nuts and cupules) with Ulmus and representatives of the Betulaceae, especially Betula and Alnus. The confirmation of Fagus, also rarely found from sites at Princeton, British Columbia, and Republic, Washington, provides the oldest well-documented occurrence of the genus, predating the Early Oligocene records of Fagus previously reported for North America, Asia, and Europe. Data provided by pollen analysis broadens our knowledge of the McAbee flora. Angiosperm pollen typically predominates over gymnosperms with the Ulmoideae and Betulaceae being the most common angiosperm pollen types. Members of the Pinaceae dominate the gymnosperm pollen record. Paleoclimatic estimates for McAbee are slightly cooler than for the Republic and Princeton localities and thermophilic elements, such as Sabal found at Princeton or Ensete and Zamiaceae found at Republic are not known from McAbee.

Floristic composition and comparison of middle Eocene to late Eocene and Oligocene floras in North America

“…The McAbee site is dominated by numerous conifers, Fagus leaves and nuts (Manchester & Dillhoff 2004), fruits and leaves of Ulmus (Denk & Dillhoff 2005), Betula, and Alnus (Dillhoff et al 2005). This site contrasts with Quilchena, which is considered the "warmest and wettest" of the Okanogan Highlands sites (Mathewes & Greenwood 2007).…”

A review of paleobotanical studies of the Early Eocene Okanagan (Okanogan) Highlands floras of British Columbia, Canada, and Washington, USA

“…1, 3), about 85 km north of Kamloops, British Columbia (Arnold 1955a(Arnold , 1955bBrown 1962;Wolfe and Tanai 1987;Gooch 1992;Wolfe et al 1998Wolfe et al , 2000McClain and Manchester 2001;Denk and Dillhoff 2005;Dillhoff et al 2005;Villeneuve and Mathewes 2005;Feng and Poulsen 2016). It is likely the various authors citing either Chu Chua or Joseph Creek refer to multiple separate outcrops exposed near the villages by the same names, which are about 15 km apart along the North Thompson River, north of Kamloops on Provincial Highway 5 (Fig.…”

“…(Denk and Dillhoff 2005), Trochodendron drachukii and associated leaves , and a reproductive structure of unknown affinities named Dillhoffia cachensis (Manchester and Pigg 2008). Both Greenwood et al (2005) and Dillhoff et al (2005Dillhoff et al ( , 2013 provided paleoclimate reconstructions for McAbee (see Gushulak et al 2016), and both Dillhoff et al (2005) and Moss et al (2005) presented pollen count data that indicated a diverse flora. While primarily focused on insects in his study of McAbee, Archibald et al (2010) used rarefaction analysis of a small collection (<200 leaves) to show plant diversity in the Early Eocene comparable to tropical rainforest sites, corroborating an extensive and detailed assessment of insect diversity.…”

“…Mathewes and Brooke (1971) reviewed these records and described several conifers and dicots. These observations were updated briefly in Greenwood et al (2005) and Dillhoff et al (2005), and Denk and Dillhoff (2005) Villeneuve and Mathewes (2005) from a bentonite that is interleaved within the shales dated the Quilchena sediments at 51.5 ± 0.4 Ma, so Early Eocene (Mathewes et al 2016) (Fig. 3).…”

“…There is considerable literature of megafossil and microfossil systematics of these sites, some of which include summaries of particular floras or complement faunal studies of fish and insects (e.g., Wolfe and Wehr 1991;Stockey 2002;Stockey and Wehr 1996;Pigg and Stockey 1996;Smith 2011;Smith et al 2012;Dillhoff et al 2005Dillhoff et al , 2013Archibald et al 2011). More recently, a greater emphasis on the paleoenvironments of the Okanagan Highland floras has appeared both in locality studies (Dillhoff et al , 2013Smith et al 2009Smith et al , 2010Gushulak et al 2016;Mathewes et al 2016) and in studies dedicated to broader issues of paleoenvironment (Greenwood and Wing 1995;Wolfe et al 1998Wolfe et al , 2000Greenwood et al 2005;Moss et al 2005;Smith et al 2012;Feng and Poulsen 2016).…”