Mars had Oxygen Long before Earth

                           The history of Mars as written in its rocks suggests that the Red planet billions of years ago before our planet did. Past comparisons of rock analysed by NASA's Spirit Rover on Mars, compared to Martian meteorites on Earth showed 5times more Ni in the meteorites, the reason for it as suggested by Oxford University is that there was more oxygen on mars than it is today. The implication is that Mars had an oxygen rich atmosphere at a time about 4000M years ago. Well before the rise of atmospheric oxygen on Earth around 2500M years ago
                           The model could help resolve a long standing discrepancy between mars meteorite compositions found on earth and that of rocks analysed on Mars. Previously these differences had led to some researchers to conclude it is not wise to make comparisons between rocks in the 2 location. The model suggests that the rocks analysed by Spirit in Mars's Gusev Crater which were about 3.7 Billion years old had a composition that was derived from early oxidation of uppermost mantle of mars. The meteorites by contrast were not as oxidized because they originated further from the mantle. Both the rocks are from same origin but the surface rocks come with a more oxygen rich environment. This result is surprising because while the meteorites are geologically young around 180M to 1400M years old. what the Spirit rover was analyzing was a very old part of mars more than 3700M years old