Stromatolite column of bacterial mats in Australia;
sponge fossils are between stromatolites
Image credit: Adam Maloof

Scientists may have uncovered the oldest animal fossils in Australia. It is believed that the primitive sponge-like creatures lived in ocean reefs about 650 million years ago.

The shelly fossils were found beneath a glacial deposit represent the earliest evidence of animal body forms in the current fossil record.

"These scientists have found that animals may have appeared on Earth 90 million years earlier than previously known," said H. Richard Lane.

The discovery proves that animal life existed before the severe "snowball Earth" event known as the Marinoan glaciation that left much of the globe covered in ice at the end of the Cryogenian.

"But then we noticed these repeated shapes that we were finding everywhere--wishbones, rings, perforated slabs and anvils. We realized we had stumbled upon some sort of organism, and we decided to analyze the fossils,? said geoscientist Adam Maloof.

"No one was expecting that we would find animals that lived before the ice age, and since animals probably did not evolve twice, we are suddenly confronted with the question of how a relative of these reef-dwelling animals survived the ?snowball Earth?,? he added.

Using specialized software techniques developed specifically for this project, the researchers "stacked" the outlines on top of one another to create a complete three-dimensional model of the creature.

The scientists decided that the fossil organisms most closely resembled sponges--simple filter-feeding animals that extract food from water as it flows through specialized body channels.

In future research, Maloof and his collaborators intend to refine the three-dimensional digital reconstruction technique to automate and increase the speed of the process.

Their findings are published in the August 17 issue of the journal Nature Geoscience.

Source: discoveryon.info