Megafauna extinction theories - patterns of extinction
It is believed that megafauna initially came into existence in response to glacial conditions.
The extinction of megafauna around the world was probably due to environmental and ecological factors. It was almost completed by the end of the last ice age. It is believed that megafauna initially came into existence in response to glacial conditions and became extinct with the onset of warmer climates.
In temperate Eurasia and North America, megafauna extinction concluded simultaneously with the replacement of the vast periglacial tundra by an immense area of forest. Glacial species, such as mammoths and woolly rhinocerous, were replaced by animals better adapted to forests, such as elk, deer and pigs. Reindeers (caribou) retreated north, while horses moved south to the central Asian steppe. This all happened about 10 000 years ago, despite the fact that humans colonised North America less than 15 000 years ago and non-tropical Eurasia nearly 1 million years ago.
Tropical and subtropical areas have experienced less radical climatic change. The most dramatic of these changes was the transformation of a vast area of north Africa into the world's largest desert. Significantly, Africa escaped major faunal extinction as did tropical and sub-tropical Asia. The Asian elephant survives until the present day, while the Asian rhinoceros survives even on the relatively small island of Java, Indonesia.
At the end of the last ice age, Australia's climate changed from cold-dry to warm-dry. As a result, surface water became scarce. Most inland lakes became completely dry or dry in the warmer seasons. Most large, predominantly browsing animals lost their habitat and retreated to a narrow band in eastern Australia, where there was permanent water and better vegetation. The diprotodon, one of Australia's megafauna, may have survived on the Liverpool Plains of New South Wales until about 7000 years ago. If people have been in Australia for up to 60 000 years, then megafauna must have co-existed with humans for at least 30 000 years. Regularly hunted modern kangaroos survived not only 10 000 years of Aboriginal hunting, but also an onslaught of commercial shooters.
Worldwide, there is no evidence of Indigenous hunter-gatherers systematically hunting nor over-killing megafauna. The largest regularly hunted animal was bison in North America and Eurasia, yet it survived for about 10 000 years until the early 20th century. For social, spiritual and economic reasons, Indigenous hunters harvested game in a sustainable manner.
Words to know:
- MEGAFAUNA - large animals such as elephant, mammoth, rhinocerous and diprotodon.
- GLACIAL - characterised by extensive masses of ice.
- TUNDRA - cold, desert, treeless plains of artic lowlands in Eurasia and North America.
- STEPPE - grasslands of temperate dry climate, such as in central Asia.
- BROWSERS - animals that feed predominantly on leaves.
Dr Stan Florek , Database Manager