Excerpts from Jim Conrad's
from the September 2, 2012 Issued from the valley of the Dry Frio River in northern Uvalde County, southwestern Texas, on the southern border of the Edwards Plateau, USA
TEXAS SPINY LIZARD
An eight-inch-long (20cm) lizard climbed up a Live Oak at the corner of a picnic shelter in the community park and he was easy-going enough to permit the picture shown above. He's similar to the common fence lizards occurring in much of North America, but for one thing: Notice how large and seemingly loose-fitting the scales are. Other fence-lizard type lizards bear smaller, closer-fitting scales.
With those large scales, its color pattern, habitat and presence here in southwestern Texas, this must be the Texas Spiny Lizard, SCELOPORUS OLIVACEUS, found only in Texas, a bit of Oklahoma, and northeastern Mexico. I read that they're often found climbing not only trees but also fences and telephone poles in the suburbs. They eat a variety of invertebrates.