These might be on the small side, but check out Mega Minis (I think more 25 than 28 but for Animals?) - they have the widest range of creatures I've ever seen. There site isn't the most user friendly but they sure have lots of critters. Also, check out Irregular 25 mm range - they have quite a zoological menu. And, again, scale can be less precise here and still work. At least I think so.
Hope that helps.