There are other (more informative) signs but the majority of them are in the indoor exhibit area... This one to the front of the outdoor paddocks is a new addition to stop Joe Public declaring the Okapi a zebra/horse hybrid etc (If they will read it is another matter!)
The only place I've seen the new style of signage so far is the Giraffe section, but admittedly I wasn't looking very hard and there probably are a few more around elsewhere in the zoo