4 minute read – 

The muskox is an adaptable animal. In the face of climate change a generalist diet with a slow metabolism helped this species survive through the last ice age and to today while other megafauna, like woolly mammoths, went extinct.

During Beringia there were two types of muskox present on the extensive grassland biome – Ovibos moschatus, the tundra muskox that roams today, and Bootherium bombifrons, the helmeted muskox. 

The helmeted muskox did not survive the Pleistocene even though it was endemic to North America and had a wider range than its relative, the tundra muskox. If you could imagine this Beringian muskox was taller and more slender than those of the living tundra muskox and its wider range spanned an area from Texas all the way to Alaska. Like many of the horn and antler bearing animals of this era it was all about BIG, oversized, dramatic displays for sexual selection. The helmeted muskox had longer deeper skulls that supported higher and more flaring horns than the tundra muskox. But, size didn’t get selected as most important for survival in this dramatically changing and climatically unstable landscape. It seems not only was smaller horns preferred through evolution but overall body size too – the less compact nature of this muskox might have played a role in its extinction along with many other large herbivorous mammals of its’ time.  

The tundra muskox crossed the Bering land bridge from Eurasia into North America about 100,000 years ago. A more focused range and smaller size as well as thicker coat than that of the Bootherium, the Ovibos remains a resident of the Arctic landscape to this day. What’s pretty incredible is that these muskox have changed, genetically, very little since their days on the Mammoth Steppe. The muskox of today’s Arctic Archipelago are however much less genetically diverse than those that lived during the last Ice Age which suggests they were not completely unscathed during this time of climatic instability. Significant population and geographical range shrinkage restricted the tundra muskox to Greenland and much of the western Northern American Arctic populations are reintroductions from those limited genetics. The two types of muskox of the late Pleistocene did not mix genetically and the reduction of both species, including the extinction of the helmeted muskox, seem to exclude humans as a driving force behind these population dynamics into the Holocene.

Ovibos moschatus, the tundra muskox, was able to ride the waves of climate change over tens of thousands of years. Their adaptability to variability, including climate and thus vegetation quantity and quality, fostered this large Ice Age mammal to survive a formidable narrow niche of the Arctic biome to present day. What might the future hold for the muskox?

Photo credit L. Caskenette

Resources:

Thanks to Dr. Grant Zazula for taking the time share incredible insights into the past, into Beringia with the YWP crew! 

Ancient DNA analyses exclude humans as the driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics. Paula F. Camposa, Eske Willersleva, Andrei Sherb, Ludovic Orlandoc, Erik Axelssona, Alexei Tikhonovd, Kim Aaris-Sørensena, Alex D. Greenwoode, Ralf-Dietrich Kahlkef, Pavel Kosintsevg, Tatiana Krakhmalnayah, Tatyana Kuznetsovai, Philippe Lemeyj, Ross MacPheek, Christopher A. Norrisl, Kieran Shepherdm, Marc A. Suchardn, Grant D. Zazulao, Beth Shapirop, and M. Thomas P. Gilberta.

Musk ox (Ovibos moschatus) of the mammoth steppe: tracing palaeodietary and palaeoenvironmental changes over the last 50,000 years using carbon and nitrogen isotopic analysis Maanasa Raghavan,, Gonçalo Espregueira Themudo, Colin I. Smith, Grant Zazula, Paula F. Campos

Tundra Muskox

Helemeted Muskox