Why did the dinosaur become extinct?

You come from all over the world and you belong to a panel of twenty elite scientists from various disciplines:  paleontology, geology, archaelogy, astronomy, and biology to name a few.  Each of you has been selected by key scientific organizations around the world to solve the age-old mystery about dinosaurs:  Why did the dinosaur become extinct?  

All of you must review the cogent theories in the field and arrive at a consensus position, which you will share with the global scientific community.   World scientists are counting on your expertise to probe the existing data and theories and pose a definitive answer to this mystery!