Timing may have helped kill off the dinosaurs

Dinosaurs may have just been unlucky that the catastrophic asteroid collision that is thought to have wiped them out arrived when it did. If it had hit the Earth earlier or later they might have survived, some scientists now think.

Steve Brusatte, a palaeontologist at Edinburgh University, says in a report in Biological Reviews that when the impact happened 66 million years ago the Earth had already suffered a dramatic loss of biodiversity and many of the big plant-eating dinosaurs, including the horned triceratops and duck-billed dinosaurs, had already disappeared.

And that meant there were fewer animals for the big meat-eating dinosaurs to prey on.

That made them just that bit less resilient when the asteroid hit what is now Mexico, setting off a disastrous chain of events including tsunamis and earthquakes, and forcing blankets of material into the atmosphere that blocked out the Sun and cooled the Earth by up to 10 degrees.

With ecosystems already weakened the dinosaurs didn’t stand a chance, as Brusatte says: “The asteroid almost certainly did it but it just so happened to hit at a bad time when dinosaur ecosystems had been weakened by a loss of diversity. If the asteroid had hit a few million years earlier, or a few million years later, then dinosaurs probably wouldn’t have gone extinct.”

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