A LATE QUATERNARY MAMMAL RECORD FROM NORTHERN ALASKA

Heretofore, data on Quaternary mammals in eastern Beringia has come almost exclusively from bones collected near Fairbanks and the Klondike. Little faunal data has been documented for northern Alaska (nAK). Here, I present results of four field seasons collecting Quaternary mammal bones along north slope rivers, principally the Ikpikpuk River.

All bones (> 2300) were collected as fluvial detrital elements. Bones erode from cutbanks during a brief spring break-up period and are transported ~0.1 - 5 km down river before being deposited on point bars. Highly variable levels of transport damage and preservation indicate repeated bouts of erosion and burial for many bones.

Adjusting for taphonomic biases, the overall bone assemblage (NISP) was composed of: 26% Ovibos moschatus, 24% Bison priscus, 21% Equus (caballus) lambei, 18% Rangifer tarandus, 10% Mammuthus primigenius, 1% other herbivoves (Mammut spp., Bootherium, Praeovibos, Alces), and 1% carnivores (Panthera leo atrox, Canis lupus, Ursus arctos, Arctodus simus). However, radiocarbon dating of 240 specimens revealed that the assemblage does not reflect a single late Pleistocene mammal community. Of 60 dated muskox, only 7 yielded finite dates, 4 of which are Holocene. Of dated mammoth, over half yielded infinite ages, but all dated horse are finite age. Bison and caribou yielded mostly finite dates; one quarter of the caribou are Holocene.

Variation in the relative, taxa-specific frequencies of radiocarbon dates suggests that late Pleistocene mammal communities in nAK may have been in a constant state of flux, and that it is inappropriate to speak of a single “late Pleistocene mammal community”. The closest approximation to such a community (ca. 30 kBP), would be ~35% bison, ~31% horse, ~20% caribou, ~8% mammoth, and ~5% muskox. Thus, it appears that the late Pleistocene bone assemblage (and consequently community structure) of nAK was not largely different than the one reconstructed by Guthrie 1968 for interior Alaska (52% Bison, 33% horse, 6% mammoth, 4% caribou, 3% muskox).

Last occurrence dates (kBP in 14C years) for extinct taxa in nAK are: bison– 10.3, horse– 12.5, mammoth– 12.4. The paucity of muskox in the Holocene assemblage (relative to caribou) suggests they occurred in low numbers until their extinction in early historic time.