Chapter 2: Mammoth Fauna in the Yukon

Palaeontology Program, Government of the Yukon. Occasional Papers in Earth Sciences No. 6. 3^rd International Mammoth Conference, Field Guide to Quaternary Research in the Klondike Gold Fields, Edited by D.G. Froese and G.D. Zazula.

John E. Storer, Yukon Palaeontologist. Dawson City, Yukon Territory, May 25-29, 2003

Vertebrate Palaeontology of the Klondike Area

John Storer: “The latest Pleistocene (late Wisconsinan) vertebrate fauna of the Klondike Goldfields is well known, at least in regard to the larger mammals (Table 2). Nearly all these mammals have been discovered during placer mining activities at various stratigrafic levels by stripping away a chiefly loessal overburden. The fine-grained deposits that are most widely distributed and produce most of the fossils date from the last (McConnell) glacial maximum about 27,000 to 14,000 radiocarbon years BP (Kotler and Burn (2000), with a younger upper layer representing the end of the Pleistocene and a sporadically exposed layer perhaps dating to the Reid-McConnel interglacial period.

The content of the later beds, which span the advance and maximum extent of the last (McConnel, or late Wisconsinan) glaciers, is consistent across the Klondike. Steppe Bison (Bison priscus, formerly called Bison crassicornis) is the most commonly preserved fossil mammal in the Klondike, as it is in the Old Crow section of Northern Yukon and the Fairbanks area of Alaska. A large bison with flattened horn cores, Bison alaskensis, may also be common in these deposits, but most of today’s workers assign all northern Ice Age bison to B. priscus.

Mammoth is not quite as common as bison, but it too is ubiquitous [is found everywhere]. The prevalence of grass-eating woolly mammoth over American mastodon in these deposits is generally taken to confirm the wide extent of treeless ‘Mammoth Steppe’ vegetation, dominated by grasses, sedges, sage, and in some areas chenopods. The overall ratio of identified woolly mammoth to mastodon fossils is at least 100:1 in the Yukon. American mastodon, known in other parts of the continent to have inhabited moister habitat, eating woody and soft vegetation, was presumably excluded from the steppe-tundra. A recent radiocarbon date of 18,460±350 on American mastodon from Gold Run Creek (YTG specimen; IsoTrace Lab number TO7745), however, points out not only that mammoth and mastodon were contemporaries throughout the Late Pleistocene in this area, but also that islands of mesic, presumably most habitat persisted in the Klondike through the last glacial maximum, even during the time of greatest dominance of the ‘Mammoth-Steppe’.

The third most common Late Pleistocene mammal of this area, the small horse Equus lambei, has a less even distribution. Its bones and teeth are far less numerous in some placers than in others, although it is seldom missing altogether. A frozen carcass of this small horse was discovered in1993, at 15 pup, Last Chance Creek. This fossil gave a first look at the animal’s coat colour and mane length (not as similar to Przewalski’s horse as expected), and yielded DNA samples clarifying the species’ closer relationship to horses than to asses or zebras (Harington and Eggleston-Stott 1996).

Other large herbivores of the Klondike are caribou (Rangifer tarandus), helmeted musk-ox (Bootherium bombifrons) and tundra musk-ox (Ovibos moschatus), and mountain sheep (Ovis. cf. O. dalli). Mountain sheep is one of the few large mammals known from the Klondike that are not found at Old Crow (Harington 1978), indicating some differences in habitat between the two areas.

Moose (Alces alces) and wapiti (Cervus elaphus) are present at many localities in the Dawson City area, but dated specimens are all latest Pleistocene or later. Saiga antelope (Saiga tatarica) is known from nearby Alaska (Porter 1988) and we may now have a specimen from Dominion Creek, but the identification is not yet firm. The western camel (Camelops hesternus) has been documented from Sixtymile River (Harington, 1978, 1997), but is otherwise by only a YTG specimen from Hunker Creek dated at 19,770±640 BP (IsoTrace Lab number TO-7740)[from the peak of the Last Ice Age].

Large carnivores are also well represented in the Last Glacial Maximum [from the peak of the Last Ice Age] of the Klondike. The most commonly discovered in my experience is the lion Panthera leo atrox, and some excellent specimens have been discovered (Harington and Clulow 1973). Also known from several localities is the largest Ice Age carnivore, the giant short-faced bear (Arctodus simus). Wolf (Canis lupus) has a scattered record, and the scimitar cat (Homotherium serum) is a very rare fossil in the Klondike.

Smaller mammals are far less well known, chiefly because we have yet to use screen-washing and other special techniques that might produce them in quantity. Burrows and occasional frozen carcasses of the Arctic ground squirrel (Spermophilus parryi) are widespread, and collared lemming (Distrostonyx torquatus), badger (Taxidea taxus), hare (Lepus sp.), and in one instance even black-footed ferret (Mustela nigripes) have been found.

A special feature of these permafrost deposits is the frequent preservation of soft tissues including fragments of muscle of bison and horse bones, and preservation of partial or even whole carcasses, and although we cannot match the Fairbanks specimen called ‘Blue Babe’ (Guthrie 1988), or the frozen mammoths of Siberia and Alaska, we do have horse (Equus lambei), Arctic ground squirrel (Spermophilus parryi), and black-footed ferret (Mustela nigripes) from the Klondike.

Older fossils from this area are less well known now. Harington (1989) has reported American lion, steppe bison, and woolly mammoth from presumed interglacial beds at Revenue Creek, northwest of Carmacks (Jackson et al. 1996).” John Storer 3^rd International Mammoth Conference, Field (2003:24, 25)

The giant beaver was the size of a black bear, with incisors as long as knife blades. It has lived in Alaska, the Yukon and the Northwest Territories, together with the woolly mammoth. Also the giant beaver was only able to live, where there is water. From: Dick Harington Canadian Geographic March/April 1999 p. 40.

The American lion resembled its modern African cousin, but weighed as much as 25 per cent more. The male did not have a mane. From: Dick Harington Canadian Geographic March/April 1999 p. 49.

Sloths are normally associated with the tropical rain forest, but the long-haired Jefferson’s ground sloth adapted to eastern Beringia’s harsher climate. This ground sloth was as large as an ox. It lived in Alaska, the Yukon Territory and the western part of Canada’s Northwest Territories. It has lived up there together with the woolly mammoth. From: Dick Harington Canadian Geographic March/April 1999 p. 41.

Klondike and Sixtymile River Area

Radiocarbon ages of dated fossils from the Klondike area, Yukon Territory.

Adapted from: John Storer 3^rd International Mammoth Conference, Field (2003:26-29) Table 2. Fossils and C14-dates from Klondike and Sixtymile River, western Yukon Territory.

John Storer concludes from his research: “The animals lived there on a tree-less “Mammoth Steppe”, where mainly grasses and sedges grew. The most numerous hoofed animal was the bison. Most of them lived up there during the last glacial maximum, at the height of the Last Ice Age. The last glacial maximum [the peak of the Last Ice Age] in the Yukon Territory was from 27,000 to 14,000 radiocarbon years ago.

The woolly mammoth (Mammuthus primigenius) has lived in the Yukon also during the height of the Last Ice Age.

The Columbian mammoth (Mammuthus columbi) has lived in the Yukon, shortly before the Last Glacial Maximum began.

According to these radiocarbon dates, the American mastodon (Mammuthus americanum) has lived in the Yukon at the same time, when the woolly mammoth was grazing up there. Also at the height of the Last Ice Age (18,460 BP, 24.980 BP). But the mastodon browsed more on shrubs and the branches of trees. So, John Storer concludes, that also during the height of the Last Ice Age a few trees have grown in the Yukon Territory, at places, where it was warmer and moister, than on the open, treeless “Mammoth Steppe”.

Also the Western camel (Camelops hesternus) has lived in the Yukon during the height of the Last Ice Age (19.770 BP), and before that (39.030 BP to 49.800 BP) according to the radiocarbon dates.

Also the lion (Panthera leo atrox) has lived in the Yukon during the height of the Last Ice Age, John Storer believes.

The American badger (Taxidea taxus) has lived in the Yukon during the Last Glacial Maximum (15.240 BP).

Comment: The badger is only able to live, where there is no permanently frozen ground. That is, south of the limit of discontinuous permafrost, that is, south of the subarctic zone.

The North American black-footed ferret (Mustela nigripes) has lived in the Yukon 30.370 BP, and 39.560 B.P.

Comment: Also the black-footed ferret is only able to live, where there is no permafrost. It lives south of the zone of discontinuous permafrost, south of the subarctic zone.

The giant short-faced bear (Arctodus simus) has also lived in the Yukon during the height of the Last Ice Age, according to the radiocarbon dates of its remains (20.250 BP to 29.695 BP, and also before that, at 44,240 BP. It has lived up there together with the brown bear (Ursus arctos).”

Is that true? Could these animals have lived in the Yukon Territory and Alaska during the height of the Last Ice Age, when it was so could and so dry at most places that trees were not able to grow there?

Portion of a painting of woolly mammoths, by J. Van Rhoon, in Mammoths by Dick Mol, Larry D. Agenbroad, and Jim I. Mead  (1993). Could this arctic plant-cover have supported those elephants during the long arctic winter? Would they have found enough to eat and to drink up there?