Bleedin' obvious, innit?
No *way* something the size of T. Rex could fly just by waving those silly little arms around, no matter how many feathers he had.
Miniaturisation was the only logical course.
And the reason they became extinct? When an egg-laying dinosaur weighing ten tons climbs into her nest to lay her eggs, if she doesn't pick a strong enough tree, the eggs are going to break. They got the chicken and egg problem the wrong way around, poor dears.
Biting the hand that feeds IT
