Life on Mars? Fossil find shows it's possible

This is a nice find, boosting existing theories, but it's certainly not news that the early life probably thrived in a reducing, oxygen-free environment. Actually, the rise of photosynthetizing blue-green bacteria and the subsequent rapid climb of atmospheric molecular oxygen levels[1] may have caused a catastrophic extinction event, wiping out most of the contemporary life forms, undefended against the dangerously reactive chemical.<p>[1] <a href="http://en.wikipedia.org/wiki/Great_Oxygenation_Event" rel="nofollow">http://en.wikipedia.org/wiki/Great_Oxygenation_Event</a>

I don't quite see how this find sheds new information on possibility of life on Mars. I though the greatest challenges to life on Mars were large temperature variations and lack of liquid water. It is already known that life could thrive in an oxygen-free environment, after all it had to start on Earth some-how.