Life As We Know It
Two hundred fifty million years ago, long before the time of the dinosaurs, the Permian mass extinction was the greatest disaster life on Earth ever faced. Ninety-six percent of marine species and 70 percent of land‑dwelling vertebrate species died.
Geological evidence shows that gigantic volcanic eruptions in what is now Siberia covered almost 800,000 square miles with molten lava. These may have triggered global climate change by emitting carbon dioxide and sulfur gases, and caused the extinction.
Bounce Back
But life eventually recovered from this catastrophe.
Paleontologists thought that the recovery was slow and stepwise, with herbivores reappearing first, and predators at the top of the food chain reappearing last, and with evolution taking more than eight million years to fill the void. But evidence published by a team of American and Swiss researchers in 2014 indicates otherwise.
They studied fossil specimens of fish, amphibians, and reptiles in museum collections. They found ample evidence that there were large aquatic predators living within the first two million years after the disaster, including bony fishes, cartilaginous fishes like modern sharks, and predatory aquatic reptiles called ichthyosaurs.
But, top predators like these can only thrive in a complex ecosystem with many levels below them in the food chain. That would mean the older ideas were wrong. Apparently, those few species that survived the catastrophe must have undergone rapid evolutionary diversification afterwards.
The researchers think earlier investigators went wrong by focusing too heavily on fossils from China. They used a worldwide sampling of evidence. But regardless of the newer findings, the recovery still took millions of years, an extremely long time in human terms.
Find Out More:
"The Permian Extinction: When Life Nearly Came To An End" (National Geographic)
"Large Predators Roamed Oceans Soon After Permian Extinction" (Astrobiology Magazine)
"End Permian Mass Extinction (The Great Dying)" (Natural History Museum, London)
"The Permian Mass Extinction, The Day The Earth Nearly Died" (BBC Horizon)
