Hangenberg Event, Benjamin Chandler, 2013
The Devonian ends in pulses—waves of extinction—like ripples disturbing the surface of a glassy puddle. Life prospers and withers and prospers. It is a 25 million year-long antiphony.
Between the dyings: flourishings, celebrations of corals and trilobites, ammonites and stromatoporoids. Some fish build armor and go to war, hiding in scaly hulls or crushing shell and bone with steam shovel jaws. Others play with new forms, gulp air and hoist themselves over muddy banks with fins-become-feet.
Between the flourishings: dyings. The seas become poison, anoxic tides of suffocation drained by glaciers, clotted by vegetable matter, and shot with asteroids. From those brinks, life rebuilds, learns new forms and tricks—then dies in the next catastrophe. Extinction and rebirth, again and again, like a steady heartbeat through the epoch: lub-dub, lub-dub, life-death, life-death.
But the choruses break. The Devonian’s see-saw seasons of life and death close with an extinction so severe it takes 15 million years for life to recuperate. The era’s final dying is dressed in green. The irony: extinction comes, not from a lack of life, but too much of it. Blankets of choking verdant scum fill the epicontinental seas. Algae conquers the placoderms—just simple, unassuming cyanobacteria that devour every nutrient, consume every inch of living space, and pull a great, final, emerald curtain over the Age of Fishes, leaving a desolate blank in the fossil record to someday puzzle Alfred Romer.