To get to the other side…
Guest post by David Middleton
“There has long been a controversy about the timing of bison arrival in North America,” said Shapiro. Bison arrival in North America marks the beginning of what geologists call the “Rancholabrean Land Mammal Age,” which is used to discriminate between different ecological periods in the continent’s history. “Until recently, the fossil records from different parts of North America disagreed with each other, with a few fossil localities suggesting that bison arrived millions of years ago, but most old fossil sites showing no evidence of bison at all,” Shapiro said. As new methods to date fossil localities emerged, the ages of the sites in North America with purportedly very old fossil bison have all been questioned, leaving the timing of bison arrival a mystery.
The new study explored fossil locations in Northern North America — the entry point for bison into the continent — and extracted DNA from two of the oldest bison fossils known on the continent. One from Ch’ijee’s Bluff in the Vuntut Gwitchin First Nation in northern Yukon, and another from Snowmass, Colorado.
“Bison used what is called the Bering Land Bridge — a vast connection of land between Asia and North America — to cross from Asia into North America. The land bridge forms during ice ages, when much of the water on the planet becomes part of growing continental glaciers, making the sea level much lower than it is today,” explained Shapiro. “After they arrived in Alaska, they spread quickly across the continent, taking advantage of the rich grassland resources that were part of the ice age ecosystem.”
While bison were not introduced by humans to North America, their rapid spread and diversification are hallmarks of an invasive species — and part of what make bison’s role in the Great Plains ecosystem so significant. “Bison arrived in North America and quickly came to dominate a grazing ecosystem that was previously reigned over by horses and mammoths for one million years,” said Shapiro.
So… These guys were actually doing the right thing by trying to wipe out an invasive species…
It’s fascinating how extreme climate changes and intercontinental migrations of invasive species could have routinely happened before humans discovered fire and invented capitalism… Fascinating.
The paper is paywalled; here’s the abstract…
Fossil and genomic evidence constrains the timing of bison arrival in North America
Duane Froesea,1, Mathias Stillerb,c, Peter D. Heintzmanb, Alberto V. Reyesa, Grant D. Zazulad, André E. R. Soaresb, Matthias Meyere, Elizabeth Halld, Britta J. L. Jensena,f, Lee J. Arnoldg, Ross D. E. MacPheeh, and Beth Shapirob,i,1
Edited by Donald K. Grayson, University of Washington, Seattle, WA, and approved February 3, 2017 (received for review December 20, 2016)
The appearance of bison in North America is both ecologically and paleontologically significant. We analyzed mitochondrial DNA from the oldest known North American bison fossils to reveal that bison were present in northern North America by 195–135 thousand y ago, having entered from Asia via the Bering Land Bridge. After their arrival, bison quickly colonized much of the rest of the continent, where they rapidly diversified phenotypically, producing, for example, the giant long-horned morphotype Bison latifrons during the last interglaciation.
The arrival of bison in North America marks one of the most successful large-mammal dispersals from Asia within the last million years, yet the timing and nature of this event remain poorly determined. Here, we used a combined paleontological and paleogenomic approach to provide a robust timeline for the entry and subsequent evolution of bison within North America. We characterized two fossil-rich localities in Canada’s Yukon and identified the oldest well-constrained bison fossil in North America, a 130,000-y-old steppe bison, Bison cf. priscus. We extracted and sequenced mitochondrial genomes from both this bison and from the remains of a recently discovered, ∼120,000-y-old giant long-horned bison, Bison latifrons, from Snowmass, Colorado. We analyzed these and 44 other bison mitogenomes with ages that span the Late Pleistocene, and identified two waves of bison dispersal into North America from Asia, the earliest of which occurred ∼195–135 thousand y ago and preceded the morphological diversification of North American bison, and the second of which occurred during the Late Pleistocene, ∼45–21 thousand y ago. This chronological arc establishes that bison first entered North America during the sea level lowstand accompanying marine isotope stage 6, rejecting earlier records of bison in North America. After their invasion, bison rapidly colonized North America during the last interglaciation, spreading from Alaska through continental North America; they have been continuously resident since then.
The Rancholabrean Land Mammal Age is the little sliver at the top of this stratigraphic column. It’s labeled “RLB”…
Useless Bison Triva
- American buffalo aren’t buffalo. They are bison.
- Buffalo wings aren’t made from buffalo or bison. They actually do taste like chicken.
- The Buffalo Bisons is either a redundant or an oxymoronic name for a minor league baseball team.
- Bison once ranged from Alaska to the U.S. east coast, perhaps even in present day Buffalo NY.