Southern Australia throws up treasure trove of fossils

[Theophilus]

PARIS (AFP) - Caves in the Sun-scorched, treeless wilderness of southern Australia's Nullarbor plain have revealed one of the world's most remarkable collections of fossils, including species of now-extinct kangaroos that lived hundreds of thousands of years ago.

The three Thylacoleo caves, located about 100 kilometers (60 miles) from the coast, were uncovered by potholers in 2002.

The find "is without precedent in Australia. Several new and previously incompletely known species are represented by whole skeletons," enthuse a team of researchers, reporting on the treasure trove in Thursday's issue of Nature.

The fossils date back to the Middle Pleistocene era, between 800,000 and 200,000 years ago.

They include 23 species of kangaroo, eight of which had never been identified before. Two of the species were tree kangaroos which had adapted to living in branches.

Other animals were several species of wallaby, a range of lizards including a large species called the King's skink (Egernia kingii), a carnivorous marsupial called the mulgara, which was related to the endangered Tasmanian devil, and two parrots.

Most of the creatures fell to their deaths from the surface, tumbling down pipe-like openings into the cave, whose floor was 20 metres (64 feet) below.

Of the 69 vertebrate species found in the caves, 21 did not make it through the Pleistocene, an era that spanned 1.8 million to 11,550 years ago and led to the Holocene, as today's post-Ice Age period is called.

One theory for large extinctions in southern Australia was that at one point the Pleistocene climate became warmer and drier, catastrophically changing the vegetation on which many herbivores (and thus their prey) depended.

But the researchers, led by Gavin Prideaux of the Western Australian Museum in Perth, say the die-out cannot be explained by this alone.

They point to the presence of the lizards, which love hot, dry climates, and to species which survived elsewhere in Australia beyond the Pleistocene and were resilient to warming.

What may have done for the species was a surge of wildfires in the Nullarbor, they suggest.

The diverse vegetation that had harboured so many species was swept away, replaced by the small, fire-resistant chenopod shrub that studs the plain today.

And Man helped sound the death knell: "Most southern species of mega-fauna were evidently extinct by or soon after 40,000 years ago, at about the time humans reached the south-central coast."

http://news.yahoo.com/s/afp/20070124/sc ... yaustralia