Late PleistoceneBison antiquusfrom Orcas Island, Washington, and the biogeographic importance of an early postglacial land mammal dispersal corridor from the mainland to Vancouver Island

Abstract

ABison antiquuscranium and partial skeleton from Ayer Pond wetland on Orcas Island, San Juan Islands, Washington, date to 11,760 ± 7014C yr BP. They lay in lacustrine sediments below peat, unconformably above emergent Everson Glaciomarine Drift (> 12,00014C yr BP). Several bison finds in similar contexts on Orcas and Vancouver Islands dating between 11,750 and 10,80014C yr BP indicate an early postglacial land mammal dispersal corridor with reduced water barriers between mainland and islands. New bison dates and published shell dates allow estimation of early postglacial relative sea-level trends for the San Juans, with a drop below modern datum ∼ 12,00014C yr BP, and assist in evaluation of marine reservoir corrections. Emergence by ∼ 60 m is suggested by data from nearby areas. A tundra-like or meadow community and succeeding open pine parkland before 11,00014C yr BP supported bison but horn-core reduction suggests suboptimal forage or restricted habitat. Expanding mixed-conifer forests after 11,00014C yr BP contributed to bison extirpation. Dispersing ungulates such as bison must have influenced island vegetation establishment and early succession. Possible evidence for butchering by early coastal people adds significance to the Ayer Pond discovery, given its pre-Clovis age.

Cytochrome-bSequence Variation in Water Shrews (Sorex palustris) from Eastern and Western North America

“…group following a single colonization. Most parsimoniously, colonization of Vancouver Island would have been via a stepping-stone route through the San Juan Islands, a recognized filter bridge (Wilson et al 2009) or possibly from the Olympic Peninsula to the south when straits were narrower following the Last Glacial Maximum. Insular populations in southeastern Alaska show no genetic divergence from mainland Cordilleran specimens.…”

Mobility and Ancient Society in Asia and the Americas

“…Radiocarbon determinations indicate that these specimens range in age between approximately 11,750 and 10,800 14 C BP (13,750-12,800 cal BP ). These discoveries, and the mountain goat bones from Port Eliza Cave, indicate that these islands were connected to the mainland at the end of the Pleistocene (Wilson et al 2009 ). Taphonomic analysis of the bison remains from the Ayer Pond site on Orcas Island dating to 11,760 ± 70 14 C BP suggest to the investigators that the bison at this site may have been butchered by early hunters (Wilson et al 2009 ).…”

“…These discoveries, and the mountain goat bones from Port Eliza Cave, indicate that these islands were connected to the mainland at the end of the Pleistocene (Wilson et al 2009 ). Taphonomic analysis of the bison remains from the Ayer Pond site on Orcas Island dating to 11,760 ± 70 14 C BP suggest to the investigators that the bison at this site may have been butchered by early hunters (Wilson et al 2009 ). Two radiocarbon dates (11,850 60 ± 14 C BP and 12,000 ± 310 14 C BP ) run on seeds and wood associated with bison and mastodon remains from the Manis Mastodon site indicate that these species were present on the Olympic Peninsula in Washington .…”

Insular mammalian fauna dynamics and paleogeography: A lesson from the Western Mediterranean islands

“…Most terrestrial animals show a low swimming ability, or are able to float but only for very short distances, as for instance some primates (Riopelle & Hubbard 1982;Zinner et al 2009;Bender & Bender 2013), antelopes (Cotterill 2003), large bo-vids (e.g. Larter et al 2003;Wilson et al 2009) and a few suids (Oliver et al 1993) sometimes do. Horses can swim over very short distances, but swimming imposes considerable physiological demands and they have neither strong swimming skills nor the propensity to venture into water (Thomas et al 1980;Tokuri et al 1999).…”