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.
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.