Fossil coryphoid palms from the Eocene of Vancouver, British Columbia

Abstract

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 (Huntingdon Formation) and the Ashcroft area in British Columbia. Pivotal results: The Sabalites fossil fronds from the Vancouver area represent fan palms (subfamily Coryphoideae, 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 Ashcroft 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.