This just out today:
http://blog.wired.com/wiredscience/2009/02/earliestanimal.html
"Fossil traces found in an oil field on the Arabian Peninsula are the oldest evidence yet of animals, pushing back the known origins of higher life to more than 635 million years ago.
"The animals' remains don't look like traditional fossils. They're more like fossil echoes: chemical traces of a compound only produced at least in modern times by demosponges, descendants of what some scientists consider to be the last common ancestor of all animals."
http://blog.wired.com/wiredscience/2009/02/earliestanimal.html
"Fossil traces found in an oil field on the Arabian Peninsula are the oldest evidence yet of animals, pushing back the known origins of higher life to more than 635 million years ago.
"The animals' remains don't look like traditional fossils. They're more like fossil echoes: chemical traces of a compound only produced at least in modern times by demosponges, descendants of what some scientists consider to be the last common ancestor of all animals."