Ahh, glad you posted the link. No, the sign I saw at the Dallas zoo was a freestanding, sandwich type sign. It has been about a year and a half since we went. Once inside main gate, it was on the left and was a wooden one. if that is no longer there, I will certainly rejoice. I wasn't even a chl last time I went to the Ft Worth zoo, so I don't think I would have even noticed that back then.
FWIW.... you can get a family membership at the Abilene Zoo, and the Dallas zoo will let you in with it. Since a family membership at Abilene is only $45, one or two trips to the Dallas zoo with your family would pay for itself. You can buy the Abilene membership through the mail, just give them a call and they will send you the forms. Many other Zoos and parks allow you in or give you a discount with the card.