They might have already been there after God made Adam and Eve.
Explanation:
Some people say that God made the dinosaurs herbivores before the Fall of Man. Before the fall, everything was perfect but after the Fall, everything spiraled into what we know now: an imperfect world. That is when the dinosaurs supposedly became carnivores.
To find more out about this, check out Answers in Genesis!
Anahuac is the name of the area the battle took place although i dont know the real name but judging by the way most battles are named i think it would be the battle of anahuac
