Environmental Engineering Reference
In-Depth Information
of that geological epoch, which lasted from about 2.58 million years to 12,000 years
before the present) it describes all heterotrophs with an adult body mass of more
than 40-50 kg. The extant megafauna includes such still abundant species as deer,
moose, and wildebeests, as well as such endangered mammals as gorillas and tigers.
The extinct megafauna, whose abundance and widespread distribution overlapped
with the evolution of
Homo sapiens
, included large herbivores with an average body
mass well in excess of 1 t (1,000 kg). Besides the woolly mammoth (
Mammuthus
primigenius
) and the woolly rhinoceros (
Coelodonta antiquitatis
), the two iconic
animals of the period, the megafauna included the straight-tusked elephant (
Paleo-
loxodon antiquus
), the giant deer (
Megaloceros giganteus
), the steppe bison (
Bison
priscus
), and the auroch (
Bos primigenius
), as well cave-dwelling lions (
Panthera
leo
) and bears (
Ursus spelaeus
).
The list of extinct megafauna in the Americas also includes the mastodon
(
Mammut americanum
), giant ground sloths (
Megatherium
), beavers and polar
bears, camelids, horses, and saber-toothed felids (
Smilodon
,
Xenosmilus
). Australia
had giant herbivorous marsupials (the wombat-like
Diprotodon
was the largest), as
well as a carnivorous marsupial lion (
Thylacoleo carnifex
). Some of these animals
(aurochs, lions) survived in much diminished numbers into the earliest part of the
Holocene, which began 12,000 years before the present: even for mammoths, the
latest survival dates in their refugium on the North Russian Plain are about 9,800
14
C years, or approximately 11,100 years before the present (Stuart et al. 2002).
But all of them were gone by the time humans began their transition from forag-
ing to a sedentary existence. Once radiocarbon dating allowed a fairly reliable
determination of ancient biomass samples preserved in a variety of sediments, the
idea that hunting caused the great extinction, as i rst argued by Owen (1861),
became quantitatively supportable: a relatively sudden and, in geological terms, a
very brief period of megafaunal extinction during the late Pleistocene appeared to
coincide with the arrival of humans in Australia and North America. Roberts et al.
(2001) concluded that all of Australia's land mammals, reptiles, and birds with a
body mass of more than 100 kg became extinct across the entire continent around
46,400 years ago, or as rapidly as within 1,000 years of human arrival. In North
America nearly half of all late Pleistocene extinctions (affecting 16 genera of large
mammals) took place between 12,000 and 10,000 years before the present, while
the arrival of the i rst skilled hunters from Asia (the Clovis people) is dated to
between 13,200 and 12,800 years ago (Thomas et al. 2008).
Beginning in the late 1950s, Martin began to argue that the rapid late Pleistocene
megafaunal extinctions in North America were caused solely by hunting (Martin
1958, 1967, 1990, 2005). His “overkill hypothesis” posited “blitzkrieg” extinction,
