FOSSIL CORYPHOID PALMS FROM THE EOCENE OF VANCOUVER, BRITISH COLUMBIA David R. Greenwood 1, * and John G. Conran† *Deptartment of Biology, Brandon University, 270-18th Street, Brandon, Manitoba R7A 6A9, Canada; and †Australian Centre for Evolutionary Biology and Biodiversity and Sprigg Geobiology Centre, School of Biological Sciences, University of Adelaide, South Australia 5005, Australia Editor: Michael T. Dunn Premise of research. Fossil fan palm fronds are well known from Eocene sites in the United States; however, although they are also known from the Paleogene Huntingdon Formation of British Columbia for over 100 years, these are poorly studied. There are early anecdotal reports of Eocene “Sabal” or Sabalites leaves from the Vancouver area, pollen from Vancouver and the interior of British Columbia, and a single megafossil palm described from the Princeton Chert, indicating past warm climates in the region. Leaves of coryphoid palms (Arecaceae) from British Columbia are described formally here for the first time. Methodology. We analyze morphologically the Eocene palm frond fossils from the Vancouver area (Hun- tingdon Formation) and the Ashcroft area in British Columbia. Pivotal results. The Sabalites fossil fronds from the Vancouver area represent fan palms (subfamily Cory- phoideae, cf. tribe Sabaleae) and are assigned to the new taxon Sabalites dawsonii. These and other Eocene palm fossils from the Pacific Northwest demonstrate that—based on prior paleoclimate analyses—coryphoid palms were growing under paleotemperatures close to their modern cold limits. Palm fossils reported from near Ash- croft are not Arecaceae, as key diagnostic characters are absent. Conclusions. These and comparable palm fossil records, coupled with analyses of paleoclimate, corroborate an early Paleogene origin of temperate climate adaptation by Coryphoideae, likely as part of the initial Sabaleae and Trachycarpeae diversifications. Keywords: Arecaceae, Coryphoideae, Eocene, fossil leaves, British Columbia, Canada. Introduction The Eocene North American record of palms (family Areca- ceae, syn. “Palmae”) includes pollen, flowers, leaves, seeds, wood, and trunk molds (Brown 1962; Erwin and Stockey 1994; Mustoe and Gannaway 1995; Harley and Baker 2001; Harley 2006; Dransfield et al. 2008; DeVore and Pigg 2010; Allen 2015; Green- wood and West 2017). Palm fossils are considered evidence for past warm climates (e.g., Wing and Greenwood 1993; Green- wood and Wing 1995; Archibald et al. 2014; Reichgelt et al. 2018; Su et al. 2019) and invoke images of tropical vegetation in regions that today support temperate, boreal, or even polar climates (e.g., Hollick 1936; Wolfe 1977; Akhmetiev 2010; Sunderlin et al. 2011, 2014; Greenwood and West 2017). The palm fossil record has also been used for phylogenetic calibra- tion points and to help untangle historical biogeography within Arecaceae (e.g., Bjornholm et al. 2006; Dransfield et al. 2008; Couvreur et al. 2011; Bacon et al. 2012; Kissling et al. 2012; Baker and Couvreur 2013; Iles et al. 2015; Cano et al. 2018; Cássia-Silva et al. 2019). Couvreur et al. (2011) proposed that subfamily Coryphoi- deae were adapted to temperate habitats by the early Paleogene, and Breedlovestrout et al. (2013) noted the disparity between es- timated mean annual temperatures (~137C) and the presence of palms in the middle Eocene part of the Chuckanut Formation in northwestern Washington State compared with early Eocene temperature estimates of 1187C (i.e., subtropical to tropical) for the Chuckanut Formation fossil flora. Bacon et al. (2012) found support for a North American 1 Central American 1 Caribbean origin for the tribe Trachycarpeae Satake, an analysis that was supported broadly by Baker and Couvreur (2013). Cássia-Silva et al. (2019) invoked niche conservatism as a factor for the lag seen between colonization of seasonally dry habitats ca. 60 Ma and diversification of Coryphoideae lineages in these habitats ca. 30 Ma. However, these analyses all depend on sound taxo- nomic treatments of palm or other monocot fossils (i.e., identifi- cation of tribe or generic groupings within tribes), as well as comprehensive knowledge of where in time and space the taxa occurred (Iles et al. 2015; Smith et al. 2018). The infrageneric phylogenetic classification of palms is based on a combined morphological and molecular data set (Baker et al. 2009). However, palm fossils are often difficult to identify below family, although some pollen and leaves can be identified to subfamily, tribe, or, rarely, genus (Read and Hickey 1972; 1 Author for correspondence; email: greenwoodd@brandonu.ca. Manuscript received March 2019; revised manuscript received June 2019; elec- tronically published December 26, 2019. Int. J. Plant Sci. 181(2):224–240. 2020. q 2019 by The University of Chicago. All rights reserved. 1058-5893/2020/18102-0006$15.00 DOI: 10.1086/706450 224