You can find these guys in the swamp area by redwoods, desert near the water and in the swamp heading to the floating islands! I incubated one wyvern egg with two of these guys. I put on my level points into melee.
These guys are quite great to have tamed, especially if your making a pack of a dinosaur. They incubate eggs, and stuff the egg under their stomach so that they get damaged instead of the egg. They also hide in the sand when submerged in water and touching the sandy floor, so that only their fin is visible. It make them practically invincible, at that state. They also deal a lot of damage; I have seen one single handedly kill a paracer. (note that the Dimetrodon got very damaged, and afterwards a carno one shot it) they also serve as air conditioning unit, so I imagine that they would be good to bring to the volcano, red woods, etc. they aren’t very fast, though, which is good if your shooting it and don’t have a cliff around. (Though, watch out for other dimetrodons around, since they will defend other dimetrodons.)