A worldwide community photographing and learning about wildlife
Not an exhibit animal, these guys are everywhere
After looking at the pics, I think you're right. There were so many turtles this weekend, it's annoying that this was the only one I got. I know that I saw red eared sliders, but this guy doesn't have the red marks. He kept pulling back when I got close, never saw him fully extended.
It is possible it could be. You saw the turtle in person! Red-ears are very common and they do get big.
From the photos of Red-Eared Sliders I have seen, the red should be visible even with only that much of the head showing. It looks like the red should start from right behind the eye. Like this:
http://www.austinsturtlepage.com/Care/ca...
http://en.wikipedia.org/wiki/Red-eared_s...
There are always color variants though. Maybe these links will help.
Perhaps a Texas River Cooter, Pseudemys texana:
http://en.wikipedia.org/wiki/Texas_river...
I thought it might be a Red-eared Slider at first but this turtle doesn't have any red on its head.