News Finding: "There must have been other ecological and evolutionary mechanisms at play.
Paper Finding: Although levels of atmospheric oxygen may have reached 10% PAL by 580 Ma, the geochemical record does not preclude oxygen levels of 0.5-4% PAL during the Cryogenian Period .
News Context: The researchers found as long as the levels remained above 0.5 percent, the sponges could survive. "There must have been other ecological and evolutionary mechanisms at play. Maybe life remained microbial for so long because it took a while to develop the biological machinery required to construct an animal.
Paper Context: Such an early evolution for sponges would be well before the general oxygenation of the deep oceans in the Ediacaran Period. Although levels of atmospheric oxygen may have reached 10% PAL by 580 Ma, the geochemical record does not preclude oxygen levels of 0.5-4% PAL during the Cryogenian Period . Indeed, oxygen levels this high may have been reached as early as the Great Oxidation Event some 2.3-2.4 billion years ago and may have persisted at these levels through much of the intervening time , with some likely swings to lower levels, however, around 1.8 billion years ago .