Fossilized plankton recovered from India’s vast Deccan Traps lava beds were exhibit A this week at a scientific meeting in Denver, where researchers placed the miniscule evidence at the scene of the crime near the time of the murder.
The victims—reptilian beasts that roamed prehistoric Earth—were suddenly and entirely snuffed out 65 million years ago. For decades, the prime suspect has been a 6-mile-wide asteroid, known as Chicxulub, that slammed into the Yucatan, creating an explosion more powerful than a trillion tons of dynamite and setting off a series of global cataclysmic events that brought down the dinosaurs once and for all.
But Princeton University’s Gerta Keller says the asteroid may be innocent—or at least it didn’t act alone. Instead, she and her research team are pointing the finger at violent volcanoes of the Deccan Traps in India, which belched out hundreds of miles of lava and spewed 10 times more climate-warming gases than Chicxulub did—enough, she says, to wipe out the prehistoric animals.
“It’s the first time we can directly link the main phase of the Deccan Traps [volcanic eruptions] to the mass extinction,“ Keller said.
The volcanoes were most active near the time the dinos disappeared. But the key question was: Which came first, the asteroid, the murders or the volcanoes? The vast expanses of geologic eras make it difficult to pinpoint the timing of relatively close events, say within tens of thousands of years.
For their answer, Keller and her group examined fossilized marine plankton excavated from layers of lava 620 miles from the center of the Deccan Traps. They already knew how old the plankton fossils were, so when the scientists placed the microscopic evidence at the scene near the end of the most massive volcanic eruptions, it allowed them to estimate more precisely when the activity occurred.
“The end of the most massive Deccan Trap eruption coincided precisely” with the extinction of the dinosaurs, the researchers say in their study.
The asteroid Chicxulub may have dealt the animals the first blow. But it may well have been volcanoes that finished them off.
By Leslie Fink, NSF
This material is provided by the National Science Foundation, an independent federal agency that supports fundamental research and education across all fields of science and engineering, in partnership with U.S. News and World Report. Keller’s research is supported by the National Science Foundation.