2. Scientists studying the rocks from the time dinosaurs became extinct noticed that they contained large amounts of a chemical called Iridium. This chemical is rare on Earth, but is common in asteroids. This interestingly enough suggests one theory that a giant asteroid hit our planet and from the impact and explosion scattered dust all over the planet, and if it was big enough would have filled the upper atmosphere blocking the sun and plunging it into a long period of freezing darkness which killed all the dinosaurs

3. The dinosaurs were wiped out by volcanoes that erupted in India about sixty five million years ago, according to new research. For the last thirty years scientists have believed a giant meteorite that struck Chicxulub in Mexico's Yucatan Peninsula was responsible for the mass extinction of species, including T Rex and its cousins. But now Professor Gerta Keller says fossilized traces of plants and animals dug out of low lying hills at El Penon in northeastern Mexico show this event happened 300,000 years after the dinosaurs disappeared.

4. http://ezinearticles.com/?Dinosaurs-Extinction---The-Asteroid-Theory&id=2242346 http://www.dailymail.co.uk/sciencetech/article-1173846/Bang-goes-theory-Dinosaur- extinction-volcano-NOT-asteroid.html