Australasian Science: Australia's authority on science since 1938

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How Australia Dried Out

Image of ancient lake

Sediments of the ancient Lake Bungunnia near Rufus River in western NSW. The white horizon is the dust layer marking the start of arid climatic regimes. Photo: Richard Stanaway

By Sandra McLaren & Malcolm Wallace

Lake Bungunnia, a megalake that existed 1–2 million years ago in today’s Murray–Darling Basin, reveals the story and timing of the onset of arid climatic conditions in south-eastern Australia.

The modern challenge of climate change demands a sound scientific understanding of the Earth’s climatic history. Historic temperature and rainfall records are very important, but so is the geological evidence of climate recorded in sedimentary rocks that are formed on the surface of the Earth.

Dr Sandra McLaren and Dr Malcolm Wallace are from the School of Earth Sciences at the University of Melbourne. This article is based on their research published recently in the journal Global and Planetary Change.

The First Breath

Image of lungfish ribs

The cranial ribs in the Australian lungfish Neoceratodus forsteri are needed to anchor the pectoral girdle, allowing the fish to raise its head to gulp air. Image adapted from Johanson et al. 2005.

By Alice Clement

A new fossil find shows that a global decline in oxygen millions of years ago drove the evolution of air-breathing in lungfishes.

Most people enjoy a dip in the ocean at their local beach or favourite holiday spot, but if you lived during the Devonian you might think twice before taking the plunge.

The Devonian Period, 416–359 million years ago, is known as the Age of Fishes. Life in the seas was very different to what we know today. The waters teemed with a plethora of beasts, including huge armoured placoderm fishes and early sharks and bony fishes. Nautiloids floated by while trilobites (ancient arthropods) scuttled around beneath them.

Alice Clement is a PhD student at the Research School of Earth Sciences of the Australian National University and Museum Victoria, where she is studying lungfish evolution and anatomy.

Entropy Theories in State of Disorder

Image of Stephen Hawking

Stephen Hawking in freefall flight on board a modified Boeing 727 jet that completes a series of steep ascents and dives to create short periods of weightlessness due to freefall. During this flight Hawking experienced eight such periods. Now one of his theories about entropy is in freefall too. Photo: NASA

By Stephen Luntz

Australian researchers have found that there is more disorder in the universe than previously realised – and that one of Stephen Hawking’s assumptions is probably wrong.

Radio broadcaster Terry Lane used to claim that he lay in bed at night worrying that entropy is increasing. It seems he now has more to worry about than he thought following the discovery that there’s more entropy in the universe than previously realised.

Meeting the Missing Link

Image of fossil skull

The cranium of the juvenile skeleton. Photo: Brett Eloff courtesy Wits University

By Paul Dirks

Paul Dirks gives a first-hand account of the expedition that found a new species of hominid linking humans and apes.

As a structural geologist I never expected to become so closely involved in such an important fossil find as Australopithecus sediba, which may be the transitional species between ape-man and the genus Homo from which we evolved (see Linking Man and Ape, p.15).

Professor Paul Dirks is Head of the School of Earth and Environmental Sciences at James Cook University, and former Head of the School of GeoSciences at Wits University in South Africa.