The Lost Leviathans of Northern Eurasia
Our investigation over the last number of months of the great extinction of large mammals and other animals which began in the late Ice Age has taken us to locations far from Ireland, from Australia far to the east, to southern Asia and Africa, and across the Atlantic Ocean to the Americas in the west. Along the way we have encountered an incredible variety of mammals, including the largest marsupial to have ever lived, possibly the largest mammal ever to have walked the Earth, as well as a dazzling array of creatures including mountainous mammoths, giant kangaroos, colossal bears, dire wolves, sabretooth cats, giant ground sloths – the list goes on and on. Finally, this month we will turn our eyes to that region to which Ireland belongs, northern Eurasia, to meet the sparkling diversity of megafaunal species which suffered extinction there from the late Ice Age onwards. And though it will become clear that the megafaunal extinctions in this region were less severe than in some other regions, it will also become very clear that the mammals lost were some of the most colossal and colourful. So, time to tell the tale of northern Eurasia’s lost leviathans – a multi-stranded story of fantastic beasts.
We can begin by putting the megafaunal extinctions in northern Eurasia in context by comparing them with those which took place in the other regions we have met so far. For instance, the extent of the extinctions in this region appear to have been greater than those which took place in Africa and southern Asia but were far less severe than those which befell Australia and the Americas. Compared to North America alone, the pattern of extinctions seems to have been far different.
For one thing, the megafaunal extinctions which took place in northern Eurasia seem to have been staggered over a far greater time span lasting tens of thousands of years rather than being concentrated mostly in a few thousand years in the very late Ice Age, and they extended well into the Holocene (c. 11,700 years ago–Present). Also, northern Eurasia simply had fewer megafaunal species than North America, the latter’s swollen roster of large mammals thought to be due to a lower rate of extinction during the Ice Age in general, allied with the influx of giant beasts from South America.
That said, though, northern Eurasia during the late Ice Age was still a region that could claim to be home to a dizzying collection of fantastic mammals, and though it was not hit as hard by the megafaunal extinctions as the Americas, these nevertheless wiped out what were undeniably its most spectacular inhabitants. Although only around 19 or 20 of its 50 megafaunal species (i.e., those weighing over 45 kilograms) suffered extinction, amounting to an extinction rate of under 40 per cent, among the casualties were three species of elephants (which include the mammoths), three species of rhinos that tipped the scales at over two tonnes, and the vast majority of other mammals weighing over 500 kilograms.
A closer look at the species that disappeared makes these losses really hit home. The three elephant species included not only the woolly mammoth, Mammuthus primigenius, but the straight-tusked elephant, Palaeoloxodon antiquus, and its cousin that lived in Japan, Palaeoloxodon naumanni, relatives of the aforementioned Palaeoloxodon namadicus, which may be the largest land mammal to have ever lived, possibly weighing in at 22 tonnes. And though Palaeoloxodon naumanni was far from the dimensions of its giant relative from southern Asia, being smaller than an Asian elephant, Palaeoloxodon antiquus was another gargantuan member of the genus. Standing around four metres tall at the shoulder and weighing around 13 tonnes, fully grown bulls would have been over twice the size of the largest mammal on land today, the African elephant, Loxodonta africana.
Other mammals of northern Eurasia to join these betrunked monsters in extinction were a number of forms that were also larger than their living relatives. These included a camel, Camelus knoblochi, which, at a weight of around 700–1,200 kilograms, could be almost twice the size of the living dromedary and Bactrian camels, which each reach around 650 kilograms in weight. From the predator guild you had the powerful cave lion, Panthera spelaea, which, although not as large as the American lion, Panthera atrox, that prowled the wilds of North America at the same time, is still thought to have been larger than living lions. Another unmistakeable predator to go extinct in the late Ice Age was the slope-backed spotted hyena, Crocuta crocuta, which had its last laugh in northern Eurasia well before the ice surrendered its grip and gave way to the Holocene.
Even greater powerhouses to be consigned to oblivion included the narrow-nosed rhino, Stephanorhinus hemitoechus, as well as its far more famous and hirsute relative which is one of the most iconic large mammals of the Ice Age – Coelodonta antiquitatis, the woolly rhino. The woolly rhino owes its name to the evolution of a long, shaggy overcoat of hair to contend with the cold, just like its contemporary the woolly mammoth, but recently it has emerged that another rhino, that too possessed a hairy coat, also vanished from northern Eurasia in the later stages of the Ice Age.
This was Elasmotherium sibericum, also known as the 'Siberian unicorn' due to its possession of just one massive horn, in contrast to the two sported by the woolly rhino. And with this rhino we have yet another example of a megafaunal mammal living in Eurasia during the late Ice Age that was larger than any of its living relatives. While the woolly rhino is thought to have been comparable in size to the largest living rhino species, the white rhino, with males reaching almost two tonnes in weight, Elasmotherium sibericum was far larger, thought to weigh a titanic 3.5 tonnes – over one tonne heavier than a male white rhino! Interestingly, though, depite its gigantic size, Elasmotherium possessed relatively slender legs compared to living rhinos, indicating that it was more adapted for running than them.
Other large herbivores to vanish from the landscapes of northern Eurasia from the late Pleistocene (Pleistocene: c. 2.6 million years ago–11,700 years ago) and Holocene included the hippo, Hippopotamus amphibius, the steppe bison, Bison priscus – a relative of today’s American bison (Bison bison) and European bison (Bison bonasus) – and its bovine relative the aurochs, Bos primigenius, the species from which Ireland’s modern domesticated cattle are descended. The spiral-horned antelope, Spirocerus kiakhtensis, also suffered extinction as did the shaggy-haired musk ox, Ovibos moschatus, which is now only found in Greenland and the Arctic region of North America but is known to have inhabited Ireland during the Ice Age. The European ass, Equus hydruntinus, also galloped its last at this time.
Of course, another spectacular herbivorous giant to suffer extinction was the giant Irish deer, Megaloceros giganteus, whose disappearance from Ireland spurred our investigation into the megafaunal extinctions in the first place. And it was not the only massive cervid to be vanquished at this time, as its somewhat smaller and less spectacularly-antlered relative, the Far Eastern giant deer, Sinomegacerus yabei, also suffered the same fate.
Another large mammal present that is thought to have been primarily herbivorous was the cave bear, Ursus spelaeus, which seems to have relied more on plants for sustenance than its closest living relatives, the brown bear and polar bear. Also, it is worth noting that although the cave bear is often touted as having been quite a bit larger than living bears, weighing up to a tonne or more, some in-depth studies have found no support for this claim, concluding that they were only about the same size as the largest living bears (the brown bear and polar bear). And though mainly herbivorous, the cave bear would have been, like its living relatives, omnivorous to some degree, taking a range of foods in its diet, including meat.
But another omnivore of very different form which likely took much more meat in its diet that suffered extinction in northern Eurasia was a relative of ours, the Neanderthal, Homo neanderthalensis. This megafaunal species was not the only one belonging to the human line to disappear either, the enigmatic Denisovans – named after the Denisova Cave in Russia where their remains were first discovered in 2010 – also thought to have joined the Neanderthals in extinction.
In the end, then, it is clear that though northern Eurasia may not have been as heavily affected by the megafaunal extinctions as some other regions, like the Americas or Australia, it is also very clear that it still lost a great diversity of spectacular and interesting forms. These ranged from mammoths to musk oxen, camels to cave lions, bison to bears, asses to aurochsen, hippos to humans, not to mention rhinos, hyenas, and giant deer. Thus, the megafaunal extinctions in northern Eurasia still altered its cast of mammals very drastically, the loss of so many large and eye-catching forms irrevocably diminishing the richness of sights and sounds on show in this vast region, which had once been home to such a wealth of fantastic beasts.