Scientists fix date for dinosaurs' extinction

Researchers say a meteor that hit 66,038,000 years ago had "dealt the death blow" to the dinosaur. photograph: getty

Researchers say a meteor that hit 66,038,000 years ago had "dealt the death blow" to the dinosaur. photograph: getty

Fri, Feb 8, 2013, 00:00

Scientists have dated the gigantic meteor crash off the Mexican coast that led to the destruction of the dinosaurs more accurately than ever before – just days before another meteor passes uncomfortably close to Earth.

Thirty years ago, scientists in Berkeley University in California linked the extinction of the dinosaurs to the 110-mile-wide Chicxulub crater off Mexico’s Yucatan coast, the result of a high-speed impact by a six-mile-wide meteor.

In a paper published today in Science, Scottish, Dutch and American researchers said that the meteor hit 66,038,000 years ago and had “dealt the death blow” to the dinosaur.

“We have shown that these events are synchronous to within a gnat’s eyebrow and therefore the impact clearly played a major role in extinctions, but it probably wasn’t just the impact,” said Berkeley’s Dr Paul Renne. The latest research clears up confusion about whether the impact came first, or the extinction of the dinosaurs which was “characterised by [their] almost overnight disappearance”, said Dr Renne.

Scientists in Glasgow University’s East Kilbride Environmental Research Centre confirmed the US findings by using a mass spectrometer to measure the ratio of radioactive potassium as against argon in rock samples.

Describing argon as nature’s “incredibly slow clocks”, Glasgow’s Dr Darren Marks said: “Many people think precision is just about adding another decimal place to a number, but it’s far more exciting than that.

“It’s more like getting a sharper lens on a camera. It allows us to dissect the geological record at greater resolution and piece together the sequence of Earth history.”

Carbon levels in the Earth’s atmosphere returned to normal “within about 5,000 years of the impact”, but this, said Dr Renne, was “in stark contrast to the world’s oceans” which took between one and two million years.

The meteor titled unimaginatively as 2012 DA14, which is due to pass within a whisker of Earth – well, 17,200 miles, is but a minnow in comparison to Chicxulub, measuring all but 150m across.

However, it is coming uncomfortably close, inside the orbit range of communications satellites which pass 22,200 miles overhead. If it did hit, it would explode with the equivalent force of 2.5 megatons of TNT. It is one of 500,000 rocks up there, scientists caution.