Among Christians, only the Biblical literalists believe that the Earth is only a few thousand years old, and they do believe in dinosaurs. The serpent in the Garden of Eden was a dinosaur, don't you know, that became a snake after God cursed it and made it eat the dust of the Earth, etc. That explains why there are no dinosaurs left, they all became snakes.
And you got this theory from where, exactly?
For the record, the young-Earth literalists usually believe that dinosaurs and humans overlapped in their existence, and point to the book of Job as evidence.
Because they ignore the science of carbon dating, for a untestable belief of the Christian folklore! Sorry, but I will take the much more believable carbon testing analysis over the folklore and myth of the Old and New Testament and the Koran!