Herpetarium-Blue Spiny Lizard and Chuckwalla

I think a collared lizard in front; and a chuckwalla at back (Ituri says San Esteban chuckwalla)

Yeah, pretty sure the back animal is Sauromelas varius but I must say I'm not totally in love with the identification of the front animal as a collared lizard, but I can't come up with a good alternative just yet.

-EDIT-
Think I found it, Sceloporus serrifer cyanogenys, Blue Spiny Lizard. The pattern on the back looks right, and ISIS shows St Louis as having this species.

you know North American herpetofauna better than me