Dinosaurs were killed off by a meteor that hit the Earth 300,000 years after the one blamed for their extinction, a scientist has claimed. Dr Gerta Keller, from Princeton University, New Jersey, insists the Chicxulub impact off the coast of Mexico 65 million years ago could not on its own have wiped out the dinosaurs. Evidence of the crater left by the giant asteroid or comet has been found under the sea off the coast of Yucatan. But according to Dr Keller, Chicxulub was only the warm-up for a much larger impact more than a quarter of a million years later. It was this meteor which left a tell-tale layer of extraterrestrial iridium in rocks around the Earth, not the earlier one, she says. However, no-one has yet found the crater from the "final straw" impact which ended the age of reptiles in one of the largest ever mass extinctions. "There is some evidence that it may have hit in India," said Dr Keller. The crater, named Shiva by one expert, is estimated to measure 310 miles in diameter. However, there is little proof of its existence. Dr Keller said marine microfossils in sediments drilled from the ocean floor showed that Chicxulub hit Earth 300,000 years before the mass extinction it was supposed to have caused.

The small marine animals that produced the microfossils escaped virtually unscathed. The Chicxulub impact combined with the Deccan-flood basalt eruptions in India - a long period of intense volcanic activity - to nudge species towards the brink, said Dr Keller. Vast amounts of greenhouse gas were pumped into the atmosphere by the Deccan volcanism over a period of more than a million years. By the time Chicxulub struck, land temperatures were 7-8C warmer than they had been 20,000 earlier. Weakened by these events, species were finally killed off by the second impact.

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I think that some of this is slightly wrong, if 1 Volcano blocked out the sun and set darkness to the planet for 3 days, how can a Meteorite not wipe out the Dinosaurs? If u throw something big + Hard at some soil, the soil would go flying and they're will be a 'crater' from the object, yeah the Earth is a lot harder but then if you have something Huge crashing into it, you'd expect a crater, rocks flying every where and hitting the Dinosaurs to death (Plus the heat from the meteorite crashing through the atmosphere would make 'Fire Ball Rocks' fly every where) more dirt from the impact would cover the skies like Mount Etna did. Plus, even though there is a crater in India, there is no clear proof of the impact, just microfossils which you can find just about everywhere.

interesting

see i believe that a meteor did strike the earth and that this caused the earth to be thrown into a cooler climate due to the dust and stuff from the impact. I dont believe all dinosaurs died at the exact same moment I believe it was a slow death due to starvation and suffication. All the bigger dinos such as Trex and the sarupods would have died first as the food ran out for the vegetarians and all the meateaters ate the dead and eachother. smaller meat eaters such as the raptor evolved faster and grew feathers to combat the cold small plat eaters may have grown feathers or fur. Dinos continued to get smaller until the good wetather returned again but by now they had eveolved so much they did not look anything like dinos. But yeah look at a bird in the park and you may be looking at the great great graet great great great great great great great great great etc grand daughther/son of a velcioraptor

Good point, i didnt exactly think that the dinos just died all of a sudden and that it wasn a slow death, but i never really stopped to think that the little ones like Velociraptors would evolve like that, and to think that a bird could be a great ... bla bla bla ... grand son/daughter of a dino. i think its cool! i believe that the might died first too, like the Therapods and Saurapods.

Sauropods actually went extinct a few million years BEFORE the K-T event. Proof that the earth was undergoing major geologic changes. It was not solely the meteor, but it did help. And another point I want the clarify, birds evolved before the mass extinction, not after.

didnt know that, cool