by Jack Le Moine
It is surprising that the earliest microbes appeared just as the Earth was beginning the last fourth of it’s 4.5 billion year existence.
In this period, the planet’s atmosphere was poison; plants appeared toward the end and transformed the bare continents as well as the atmosphere. Plant photosynthesis takes in carbon monoxide and puts out oxygen.
Meanwhile, in the oceans, the microbes evolved into giant sea monsters, while others made their first tentative presence on the shores.
MYA = Million Years Ago
BYA = Billion Years Ago
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