Mass extinction of dinosaurs caused by giant asteroid?

The Alvarez hypothesis posits that the mass extinction of the dinosaurs and many other living things during the Cretaceous–Paleogene extinction event was caused by the impact of a large asteroid on the Earth. Evidence indicates that the asteroid fell in the Yucatán Peninsula, at Chicxulub, Mexico. Prior to 2013, it was commonly cited as having happened about 65 million years ago, but a 2013 paper by Renne et al. gave an updated value of 66 million years.

The size of the asteroid. The answer was about 10 kilometers (6 mi) in diameter, about the size of Manhattan. Such a large impact would have had approximately the energy of 1 x 10⁸ megatons, i.e. about 2 million times as great as the most powerful thermonuclear bomb ever tested.

The most easily observable consequence of such an impact would be a vast dust cloud which would block sunlight and prevent photosynthesis for a few years. This would account for the extinction of plants and phytoplankton and of all organisms dependent on them (including predatory animals as well as herbivores). But small creatures whose food chains were based on detritus would have a reasonable chance of survival. 

Giant asteroid approaching earth

Impact on earth

Pingualuit crater in Nunavik, northern Quebec, Canada, looking west. It contains a lake named Lake Pingualuk.

Meteor Crater is a meteorite impact crater approximately 37 miles east of Flagstaff and 18 miles west of Winslow in the northern Arizona desert of the United States. 

Crater in Northern Arizona Desert

NASA image of simple and complex crater structure. The caption read, "As shown in the above diagram, the main difference between the simple crater and the complex crater, is that the complex crater exhibits central peak uplift in the center of the crater."

Photo Source: Collected from Internet