Rio Grande Nature Center
I was told by a naturalist that it is a sceloporus ungulates. But that is the name for an eastern fence lizard.
He blends in with the stump pretty well. Maybe he is not called a stump or tree lizard because he is much easier to see when on a fence?
The eastern fence lizard (Sceloporus undulatus) is a medium-sized species of lizard found along forest edges, rock piles, and rotting logs or stumps in the eastern United States. It is sometimes referred to as the prairie lizard, fence swift, gray lizard, or pine lizard.