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Late Devonian Extinction

A series of extinctions 360-375 million years ago, removed 70% of all species. Major environmental changes including frequent sea level changes, anoxic ocean bottoms, abnormally large carbon burials all contributed to the extinction; however it is not clear what caused the environmental changes in the first place. Possible causes:

Plant evolution - Devonian sough rapid evolution of plants, in the early Devonian the tallest plants were 30 cm but by late Devonian plants escalated to 30 m (90 feet). Archaeopteris forests quickly covered the globe.

Effect on weathering - these plants contributed to heavy weathering as plant roots broke up soil/rock releasing huge quantities of nutrients in to the rivers and the ocean, the ecology of the time was not able to absorb the nutrients subsequently leading to anoxia.

Effect on CO2 - the greening of the planet absorbed CO2 leading to a permanent chilling to the planet.