Triceratops horn find supports meteor extinction theory

Hell Creek fossil not actually coated in iridium, but ...

A team of boffins from Yale University look likely to have uncovered the world's youngest dinosaur and in the process provided support for the Alvarez hypothesis – that the dinosaurs were wiped out as a result of a massive meteor strike some 65 million years ago.

Since the early 1990s, it has been generally accepted that an asteroid strike in Mexico killed off the dinosaurs. It created the K-T boundary – a transition line in the earth's crust rich in iridium – a metal not common on earth but often found in asteroids and meteors.

The only problem with this hypothesis was a lack of dinosaur fossils anywhere near the line – which suggested the giant lizards might have died out thousands of years before the space strike.

But now a team from Yale led by Tyler Lyson has found a likely triceratops horn just 13 centimetres from the KT line.

Lyson said: "The fact that this specimen was so close to the boundary indicates that at least some dinosaurs were doing fine right up until the impact." Exact aging is impossible but the team believe the creature must have lived within some tens of thousands of years to a few thousand years before the impact.

The team is now looking at over fossils in Hell Creek, Montana and will use soil analysis to judge exactly how far from the boundary those bones lie.

But Gregory Retallack, a soil scientist from the University of Oregon, warned against reading too much into the finding. He told Science Now that finding one bone did not prove either the gradual or the meteor impact theory. He said researchers would expect to find fewer bones close to the line, whether it was an instant or a gradual extinction.

The team's press release is here. ®

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