Theories on the big Dinosaur extinction 65 Million Years ago.

My theory is this...

The Planet itself is a living creature. 65 million years ago, it was at a size where, as we see with a human baby, puppy fat grows. This expansion in the planet's size caused all the larger dinosaurs to be crushed under the weight of the new gravitational pull from the planetary expansion. Then as time passed, the child Earth lost its puppy fat and it shrunk in size allowing the surviving smaller dinosaurs, who during the expansion period evolved with lighter hollow bones. With a lighter gravitational pull on the now contracted Earth, these smaller dinosaurs evolved into the birds we now see around the world. Just a thought.