Deltanine

Green was the dominant color for plants both on land and in the ocean until about 250 million years ago when changes in the ocean's oxygen content - possibly sparked by a cataclysmic event - helped bring basic ocean plants with a red color to prominence - a status they retain today.
Studying ancient fossils plus current species of microscopic ocean plants called phytoplankton, the scientists found evidence that a "phytoplankton schism" took place after a global ocean oxygen depletion killed 85 percent of the organisms living in the ocean about 250 million years ago at the end of the Permian era.

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