Dinosaurs may have been wiped out by a massive 25 mile wide meteor - four times bigger than the asteroid previously though to be behind their extinction।

The deepest part of the Shiva basin, in red in this elevation diagram, is three miles below the surface of the Indian Ocean Photo: KYLE MCQUILKIN

Researchers believe they have discovered the world's biggest crater off the coast of India which they think may be responsible for the extinction of dinosaurs 65 million years ago.

The mysterious Shiva basin, named after the Hindu God, has a diameter of 310.7 miles along the seafloor and has a central peak of some 3 miles, as tall as Mount McKinley, the highest mountain in North America.

This dwarfs the meteor that was thought to have killed off the dinosaurs which measured between five and six miles and lies in the Yucatan Peninsula in Mexico.

That impact left a crater with a diameter of 180 kilometres.

Sankar Chatterjee of Texas Tech University, who led the research, said: "If we are right, this is the largest crater known on our planet.

"Rocks from the bottom of the crater will tell us the telltale sign of the impact event from shattered and melted target rocks. And we want to see if there are breccias, shocked quartz, and an iridium anomaly."

Asteroids are rich in iridium, and such anomalies are thought of as the fingerprints of an impact.

Mr Chatterjee believes the impact of an asteroid or comet of this size would have vaporized the Earth's crust on collision, killing most life and leaving ultra-hot mantle material to well up in its place.

The force of the impact broke the Seychelles islands off of the Indian tectonic plate and sent them drifting towards Africa. Much of the 30-mile-thick granite layer in the western coast of India was also destroyed.

Most of the crater lies submerged on India's continental shelf, but some tall cliffs rise above the sea, bringing active faults and hot springs. The area is a rich source of oil and gas reserves.

The team plans to visit India again to drill into the centre of the crater for clues to prove the basin was formed by a gigantic impact.

Mr Chaterjee will present his research this month at the Annual Meeting of the Geological Society of America.