Cyanobacteria - "blue green algae" - does photosynthesis. But when did these become chloroplasts, enabling plants?
Eliane Evanovich Jr. and Joao Farias Guerreiro Sr. offer an answer: 1342 Mya, on the other end 3225 million years after the solar-system formed.
You can see that this "Late Mesoproterozoic" is already well into the Earth's lifespan. Plants are only, what, twice as old as the Ediacaran fauna. The Earth might not have had much of a dynamo, and the sun was colder; but we already had a moon, and this part of space wasn't being hit by meteors so much.
Evanovich and Guerreiro say that a chloroplast needs zinc and molybdenum. Earth had oceans by then, but not the zinc or the moly'. Last May, the University of Münster reported that the molybdenum in our upper mantle came from the outer solar system. But I don't hear that it got here so recently. The Münstermen were thinking Theia, which is known to have come at us from an outer orbit - although that study was less clear on how far out.
So I guess some volcanoes churned it back up and into the oceans, with the zinc.
No comments:
Post a Comment