Geoscientists working in southern Australia say they have discovered the remains of primitive sponge-like creatures that lived in ocean reefs about 650 million years ago. If it holds up, the finding would mark the oldest animal fossils ever found. It also would be older than a couple of reef-dwelling organisms that date back 550 million years.
The findings by Adam Maloof and Catherine Rose were published in the August 17 issue of the journal Nature Geoscience. In a statement, Maloof said the pair came upon the discovery during the course of another project focused on the end of an ice age 635 million years ago.
"We were accustomed to finding rocks with embedded mud chips, and at first this is what we thought we were seeing," Maloof said. "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. 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."