Extinction of dinosaurs was caused by a series of changes in climate and environment like changing sea levels, varying temperatures and extensive volcanic activity ending up in a perfect storm.

Dr Steve Brusatte, of the University of Edinburgh's School of GeoSciences, said that the dinosaurs were victims of colossal bad luck and not only did a giant asteroid strike, but it happened at the worst possible time, when their ecosystems were vulnerable.
Dr Richard Butler of the School of Geography, Earth and Environmental Sciences at the University of Birmingham asserted that there had been intense scientific debate about the cause of the dinosaur extinction and although their research suggested that dinosaur communities were particularly vulnerable at the time the asteroid hit, there was nothing to suggest that dinosaurs were doomed to extinction.
The study is published in Biological Reviews.
Source-ANI