title: Fossil palm beetles refine upland winter temperatures in the Early Eocene Climatic Optimum.
abstract: Eocene climate and associated biotic patterns provide an analog system to understand their modern interactions. The relationship between mean annual temperatures and winter temperatures-temperature seasonality-may be an important factor in this dynamic. Fossils of frost-intolerant palms imply low Eocene temperature seasonality into high latitudes, constraining average winter temperatures there to >8 °C. However, their presence in a paleocommunity may be obscured by taphonomic and identification factors for macrofossils and pollen. We circumvented these problems by establishing the presence of obligate palm-feeding beetles (Chrysomelidae: Pachymerina) at three localities (a fourth, tentatively) in microthermal to lower mesothermal Early Eocene upland communities in Washington and British Columbia. This provides support for warmer winter Eocene climates extending northward into cooler Canadian uplands.
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada V5A 1S6;Royal British Columbia Museum, Victoria, BC, Canada V8W 1A1;Entomology Department, Museum of Comparative Zoology, Cambridge, MA 02138; sba48@sfu.ca.
authors.forename: S Bruce
authors.initials: SB
authors.lastname: Archibald
authors.affiliation: Biology Department, University of San Diego, San Diego, CA 92110;
authors.forename: Geoffrey E
authors.initials: GE
authors.lastname: Morse
authors.affiliation: Biology Department, Brandon University, Brandon, MB, Canada R7A 6A9; andBarbara Hardy Institute, University of South Australia, Adelaide, SA 5000, Australia.
authors.forename: David R
authors.identifier: http://orcid.org/0000-0002-8569-9695
authors.initials: DR
authors.lastname: Greenwood
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada V5A 1S6;
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Mathewes
mesh_terms: D000818:Animals; D028023:Arecaceae; D001272:Atmosphere; D044822:Biodiversity; D001955:British Columbia; D002245:Carbon Dioxide; D002980:Climate; D001517:Coleoptera; D017753:Ecosystem; D005580:Fossils; D019015:Geologic Sediments; D010163:Paleontology / Q000379:methods*; D011058:Pollen; D012621:Seasons; D028024:Serenoa; D013696:Temperature
chemical_list: D002245:Carbon Dioxide
keywords: Okanagan Highlands; paleoclimate; palm bruchines; palm pollen