Mere moments could have made the difference for the dinosaurs' survival, with scientists saying if the killer asteroid hit further from land their extinction might not have happened.
In a new BBC 2 documentary called The Day The Dinosaurs Died, scientists drilled into the Chicxulub crater which is associated with the ancient beasts' extinction 66 million years ago.
Rocks recovered from under the Gulf of Mexico show just how the impact, equivalent to 10 billion Hiroshima bombs, shows it couldn't have hit in a worse place, the BBC reports.
The 15km-wide asteroid hit on land and in the shallow ocean unleashing massive volumes of sulphur from the mineral gypsum into the atmosphere, blocking out the sun and creating a "global winter".
"In this cold, dark world food ran out of the oceans within a week and shortly after on land. With nothing to eat anywhere on the planet, the mighty dinosaurs stood little chance of survival," documentary presenter and evolutionary biologist Ben Garrod says.
"Had the asteroid struck a few moments earlier or later, rather than hitting shallow coastal waters it might have hit deep ocean.
"An impact in the nearby Atlantic or Pacific oceans would have meant much less vaporised rock including the deadly gypsum. The cloud would have been less dense and sunlight could still have reached the planet's surface, meaning what happened next might have been avoided".
The documentary will screen in the UK on Monday.