Ancient fossils discovered in Australia

Microscopic fossils have been discovered in samples of rock collected near a remote watering hole in the middle of the Australian Outback.

Scientists said the microscopic fossils belonged to primitive bacteria that lived more than 3.4 billion years ago, when the Earth had emerged from a period when it was probably too hostile for life. It is generally agreed among scientists that the earth is about 4.5 billion years old and the earliest forms of life came into being from about 3.8 billion years ago.

In that light, these fossils are not the oldest evidence of life nor are they the oldest microfossils discovered. The significance of these fossils lie elsewhere. They are important because they provide a glimpse of the metabolisms that were employed by some of the earliest life on Earth. Oxygen was introduced into the earth's atmosphere much later into the early history of the world. Before that the bacteria present on earth were sulphur based. These microfossils substantially prove this theory.

The fossils were found in rocks that were originally formed in shallow seas and suggest beaches may have been the key habitat where Earth's first lifeforms thrived, said David Wacey, of the University of Western Australia.

"The environment in which the microfossils were found is important - it extends the record of life in shoreline or beach-like environments by about 200 million years. This suggests that beaches could have been the setting for the origin of life itself," he said.

Professor Brasier says their discovery also has implications in the search for life on other planets, giving scientists an indication of what evidence for such life might look like.