ICE AGE MAMMALS OF YUKON An x-ray image of a complete arctic ground squirrel mummy found preserved in its burrow. This mummy is 47,000 years old! ISBN 978-1-55362-705-0 Written by Grant Zazula and Tyler Kuhn All Photos © Yukon Government 2014, unless otherwise noted All artwork by George “Rinaldino” Teichmann MAP OF BERINGIA Beringia today (top) with submerged land bridge and Beringia 18,000 years ago (bottom) with exposed land bridge. Map courtesy Yukon Geological Society. A Yukon horse jaw uncovered by placer miners on Quartz Creek near Dawson City. TABLE OF CONTENTS The Ice Age . 6 Iconic Animals of The Ice Age . 8 Woolly Mammoth . 8 American Mastodon . 10 Steppe Bison . 12 American Scimitar Cat . 14 Animals of the Interglacial Periods . 16 Jefferson’s Ground Sloth . 18 Giant Beaver . 20 Yukon’s Camels . 22 Flat-headed Peccary . 24 Elk . 26 Caribou . 28 Walrus . 30 Animals of the Glacial Periods . 32 Yukon Horse . 34 Arctic Ground Squirrel . 36 Saiga Antelope . 38 Beringian Lion . 40 Short-faced Bear . 42 Grey Wolf . 44 Humans . 46 THE ICE AGE n the far northwest corner of Canada lies a fascinating Yukon’s Ice Age Story place that is treasured by the world for its stunning For most of the Ice Age, Canada was covered by ice beauty and vast, unspoiled wilderness—a place called several kilometers thick. Glaciers in the Arctic advanced Yukon. Many come to Yukon to view the iconic wildlife and retreated with the cooling and warming of the Iof the boreal forest, from grizzly bears, wolves and lynx, Earth’s climate. But a small corner of northwest Canada, to caribou and moose. But Yukon has not always looked in Yukon, escaped these glaciers and remained home to this way. The picture of life in the North has changed a vast array of both strange and familiar ancient beasts. immensely over thousands of years. These changes are Even with Yukon cut off from the rest of North America well documented in the stories of the First Nations people by these glaciers, it was not completely isolated. During who have traversed the land for generations. Change is also these cold times, when glaciers blocked the way south, revealed by ancient fossils and bones of animals that roamed Yukon and neighbouring Alaska were connected to Asia Yukon long ago. Probably the best understood period of by an exposed “land bridge” across the Bering Strait. Yukon’s ancient history is the Ice Age. Before we explore this This ice-free land, stretching from Yukon to Siberia, is vanished version of Yukon, it is important to take a moment known as Beringia. to set the stage and explain a bit about the Ice Age. When the Earth completed its transition from the last If we consider the past thousands or millions of years, glacial to the present warm period approximately 11,000 the Earth’s climate is far from stable. During the last 2.5 years ago, the massive glaciers covering North America million years alone, there were many times when the melted. The Bering land bridge was again flooded by the Earth’s temperature dropped well below what we think of sea, and Yukon’s strange ancient beasts vanished, but as normal. Imagine Earth as much as five degrees colder not entirely. than it is today! But there were also times between these cold periods when climate was as warm as today. Together Now, throughout Yukon’s short, intense summer months, these repeated cycles of cold “glacial” times and warm fossil bones, teeth and skeletons are released from the “interglacial” times are what we have come to call the Ice frozen ground, from Herschel Island to the goldfields Age, or the Pleistocene epoch. This ice age climate has of the Klondike. This frozen ground, or permafrost, shaped the plants, animals, and landscapes that are familiar provides a window into life during the Ice Age. New to us today. fossils continually reveal incredible stories of ancient mammals that once called Yukon home. In fact, Yukon is Canada’s most important source of ice age mammal Did You Know? fossils. Other areas of Canada, such as Alberta’s Climate has always been in a state of fluctuation. The badlands, are famous for their much older dinosaur Ice Age or Pleistocene wasn’t always cold, but nearly 80 bones. Yukoners can take great pride in the fact that per cent of the Ice Age was dominated by glacial times their home produces the most abundant and most when temperatures were colder than present day. For the significant ice age mammal fossils in Canada. remaining 20% of the Ice Age, temperatures were similar to today. We are presently living in an interglacial warm period known as the Holocene which started 11,000 years ago. 6 Iconic Animals of the Ice Age Digging Deeper: Permafrost is ground that remains frozen throughout the year. Permafrost is one of the most important and unique aspect of the fossil record of Beringia. Because some ancient animals were nearly instantly frozen when they died, permafrost provides the ideal situation for preserving bones, and sometimes soft tissues such as hair, skin and muscles. Nearly complete frozen carcasses of Ice Age mammals have been found in Beringia. Present 25ka 50ka 100 ka 150ka* Figure: Glacial and Interglacial Cycles for the last 150ka* Archaeologist Jana Morehouse shows off a recently discovered 3 metre long mammoth tusk. *150ka = 150,000 years ago When you see these icons and coloured tabs, it these topics, be sure to check out the additional means there is more information available on information on our website www.beringia.com, our website. check us out on Facebook at facebook.com/ yukonberingia, or send us a note on twitter Follow along to learn more about these Ice Age @yukonberingia. mammals! If you want to delve deeper into any of 7 Status: Extinct In Yukon: 300,000 – 12,000 years ago WOOLLY MAMMOTH Mammuthus primigenius or many people, the woolly mammoth is the prime may have been used for display, defense, or possibly to example of an ice age mammal. These large, furry sweep away snow to get at grass in the winter. Tusks elephants were perfectly adapted to living on the preserve a wealth of information about a mammoth’s life Mammoth Steppe of ice age Yukon. About the size because they are a lot like trees, with layer upon layer of Fof an African elephant, a woolly mammoth stood a little growth rings forming over time. By studying these growth over three metres tall at the shoulder and consumed more rings, scientists can learn about a mammoth’s health than 200 kilograms of grass each day. The discoveries of through its entire lifespan, the climate a mammoth lived complete frozen woolly mammoth carcasses have revealed in, and where it migrated to and from. detailed glimpses into the life and appearance of these iconic animals. Some preserved physical characteristics can even be linked back to specific adaptions to life in the cold— for example their thick fur, small ears and short tail were all Did you know? adaptations to minimize heat loss. Scientists have found evidence that like modern elephants, mammoths sometimes Woolly mammoths, like many giant animals of the Ice Age, used their tusks as a “nose-rack” for resting went extinct as the climate warmed at the end of the last their trunk. glacial period. Fossils from North America and Asia indicate woolly mammoths disappeared from the mainland around They only used the right or left tusk depending 12,000 years ago. Remarkably, they managed to survive on on whether they were right- or left- “handed”. small Arctic islands off northern Siberia until around 4,000 years ago. Did you know? Today, Yukon is mostly boreal forest, but during glacial periods of the Ice Age the region that remained free of ice making it an ideal habitat for woolly mammoths. This cold, treeless grassland plain takes its name from the mammoth—it is known as the Mammoth Steppe. Yukon’s Woolly Mammoth History The long, curved tusks of woolly mammoths are probably the most immediately recognized ice age fossil from Yukon. A single tusk from an adult male tusk can stretch Paleontologist Tyler Kuhn poses with a mammoth tusk found at over 3.5 m long and weigh more than 100 kg. These tusks a placer mine in Dawson City, Yukon. 8 Iconic Animals of the Ice Age Status: Extinct In Yukon: 300,000 – 12,000 years ago George Teichmann’s Beringia Winter Scene, 1996. Mammoth teeth, or molars, are common fossils in Yukon. Alaska around 300,000 years ago from those ancestors. They These mammoth molars are very distinctive, with vertical eventually spread back across Beringia and into Europe. hard enamel plates that formed a flat grinding surface for Woolly mammoths also had a close cousin, the larger bodied breaking down tough grasses. Analysis of mammoth baby Columbian mammoth (Mammuthus columbianus), which lived molars from Old Crow revealed that young mammoths may further south in North America. Recent genetic evidence is have nursed on their mother’s milk for much longer than suggesting that woolly and Columbian mammoths interbred in today’s African elephants – nursing almost exclusively until regions where they overlapped. about three years of age. This prolonged nursing may have been an adaptation to help survive the long dark winters, Recent Discoveries when food was scarce. Or, maybe young mammoths Thanks in part to the amazing preservation of permafrost, preferred to stay close to their mothers, so as to avoid the North’s natural deep freezer, geneticists have come falling prey to a hungry Beringian lion or other predator? tantalizingly close to resurrecting the woolly mammoth! We now know the complete sequence of mammoth DNA—their The first mammoths crossed Beringia into North America genome—including the DNA sequence for mammoth hair around 1 million years ago.