EDMONTON — University of Alberta scientists say they have
uncovered the fossilized trails of an ancient slug that proves
complex life evolved 30 million years earlier than established
by previous discoveries. The tiny tracks, found in a South
American rock formation, date back 585 million years. The fossil
find reported Thursday in the journal Science, confirms what
scientists had theorized was possible — but not previously
proved — allowing for an important addition to the evolutionary
chronology. "We now have the oldest physical evidence that
multi-cellular life that could move was around between 600
million and 585 million years ago," said U of A
geomicrobiologist Kurt Konhauser, one of the article's seven co-
authors. Before these animals evolved, there were single-celled
life such as bacteria and eventually other creatures such as
sponges, which could not move. "Then by 585 million years ago,
we have evidence something bigger was in existence," Konhauser
said. Bigger, of course, is a relative term. The sl