* Astronomy

Extinct woolly mammoths and ancient American horses may have been grazing the North American steppe for several thousand years longer than previously thought. After plucking ancient DNA from frozen soil in central Alaska, a team of researchers used cutting-edge techniques to uncover "genetic fossils" of both species locked in permafrost samples dated to between 7,600 and 10,500 calendar years. This new evidence suggests that at least one population of these now-extinct mammals endured longer in the continental interior, challenging the conventional view that these and other large species, or megafauna, disappeared from the Americas about 12,000 years ago.

"We don't know how long it takes to pinch out a species. Extinctions often seem dramatic and sudden in fossil records, but our study provides an idea of what an extinction event might look like in real time, with imperiled species surviving in smaller and smaller numbers until eventually disappearing completely" - Ross MacPhee, Curator of Mammalogy at the American Museum of Natural History.

At the end of the Pleistocene, the geological epoch roughly spanning 12,000 to 2.5 million years ago, many of the world's megafauna, such as giant sloths, sabre-toothed cats, dire wolves, stag-moose, and mammoths, vanish from the geological record. Some large species such as Equus caballus, the species from which the domestic horse derives, became extinct in North America but persisted in small populations elsewhere. Because of the apparent sudden disappearance of many megafaunal species in North America, some scientists have proposed cataclysmic explanations like human overhunting, an extraterrestrial impact, and the introduction of novel infectious diseases. The swiftness of the extinctions, however, is not suggested directly by the fossils themselves but is inferred from radiocarbon dating of bones and teeth discovered on the surface or buried in the ground. Current "macrofossil" evidence places the last-known mammoths and wild horses between 13,000 and 15,000 years ago.

Source: American Museum of Natural History

Starvation 'wiped out' giant deer

The giant deer, also known as the giant Irish deer or Irish elk, is one of the largest deer species that ever lived.
Yet why this giant animal, which had massive antlers spanning 3.6m, suddenly went extinct some 10,600 years ago has remained a mystery.
Now a study of its teeth is producing tantalising answers, suggesting the deer couldn't cope with climate change.
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The diprotodon, a 2.5 tonne, wombat-like creature that was the largest marsupial on earth at 1.8 metres tall, above, consisted of a single species when it roamed Australia during the Pleistocene era more than 100,000 years ago, Gilbert Price, of the University of Queensland, has found.
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