How did the dinosaurs die? Scientists have a new theory

New research suggests that dinosaurs that were wiped out 66 million years ago by an asteroid or a comet may have also faced another natural disaster during their demise. Atmospheric effects are also hard to differentiate from each other as both events happened at the same time.

IT has been a bone of contention between dinosaur experts for the past 35 years – did dinosaurs become extinct as a result of a massive asteroid impact or were they snuffed out by stupendous volcanic eruptions?

Such massive eruptions in combination with the asteroid impact would have smothered Earth in toxic fumes and thick layers dust, the researchers say, killing off species after species. Over the course of 420,000 years following the asteroid, they concluded, the Deccan eruptions produced enough lava to cover the continental USA with a molten, 600-ft-deep (183 m) ocean.

“If our high-precision dates continue to pin these three events-the impact, the extinction and the major pulse of volcanism-closer and closer together, people are going to have to accept the likelihood of a connection among them”, said Renne.

Gerta Keller, a Princeton geologist who has long championed the idea that the volcanism, and not the Chicxulub impact, led to the mass extinctions, said in an email that “there is still the big problem of demonstrating that this impact could have triggered the intense eruptions that led to the mass extinction”. Researchers believe that the impact abruptly changed the volcanoes’ plumbing systems, drastically altering volcano chemistry and frequency of eruptions. Then the father-son team of Luis and Walter Alvarez reported anomalous amounts of iridium in a clay layer right at the geological boundary between the Cretaceous and what is now called the Paleogene period. The new study based its findings on these measurements and is more accurate compared all previous studies. Scientists say that in the moment of the impact, the object may have caused magnitude 11 earthquakes across Mexico and magnitude 9 earthquakes all around the world.

Based on their analyses, scientists arrived to the conclusion that the volcanic activity that killed the dinosaurs occurred about 50,000 years before the asteroid hit the Earth. But what followed were the largest volcanic eruptions the Earth had seen in 60 million years.

In the Science paper, they describe major changes in the Deccan Traps volcanism, which was probably “bubbling along happily, continuously and relatively slowly” before the extinction, Renne said.

Professor Renne and colleagues examined lava samples from the Deccan flood basalt using high-resolution argon radio isotope dating techniques.

“These changes are consistent with an accelerated rate of magma production and eruption that you could get from a large quake such as would be created by the Chicxulub impact”, he said.

The theory sounds feasible since earthquakes are known to induce volcanic eruptions.

The two-punch theory was developed and is now being pushed by geologists and other researchers at the University of California, Berkeley.