Namibia sponge fossils are world's first animals: study
Scientists digging in a Namibian national park have uncovered sponge-like fossils they say are the first animals, a discovery that would push the emergence of animal life back millions of years.
The tiny vase-shaped creatures' fossils were found in Namibia's Etosha National Park and other sites around the country in rocks between 760 and 550 million years old, a 10-member team of international researchers said in a paper published in the South African Journal of Science.
That means animals, previously thought to have emerged 600 million to 650 million years ago, actually appeared 100 million to 150 million years before that, the authors said.
It also means the hollow globs -- about the size of a dust speck and covered in holes that allowed fluid to pass in and out of their bodies -- were our ancestors, said co-author Tony Prave, a geologist at the University of St Andrews in Scotland.
"If one looks at the family tree and projects this backward to where you have what's called the stem group, the ancestor of all animals, then yes, this would be our great-great-great-great-great-great-great grandmother," he told AFP.
Prave said fossil evidence that animals emerged as long as 760 million years ago fit together neatly with what geneticists had hypothesised by looking at "molecular clocks", a means of gauging a species' age by looking at the percentage difference between its DNA and that of another species.
"The aspect of this that's rather satisfying, at least intellectually, is that it is in broad agreement with what geneticists would tell us based on looking at molecular clocks when we should see the first advent of large multi-cellular life forms," he said.
(c) 2012 AFP