What is the main idea of the news item? [originaltext] Scientists say they ca

Scientists say they can now definitively back the long held theory that a huge asteroid striking the earth some 65 million years ago was responsible for wiping out the dinosaurs and more man half of all animal species on the planet. The scientists finally discounted an alternative theory that volcanic eruptions caused the dinosaur’s demise.
    The popular conception is that dinosaurs reigned supreme until they were suddenly eradicated from the face of the planet. The theory goes that a giant asteroid crashed into the earth, wiping out half of all life on earth. Some scientists though say that those evidences that dinosaur survived the asteroid impact and became extinct some 300,000 years later. But a new analysis of all the available research has backed the view that it was a giant asteroid that wiped out the dinosaurs.