You have an interesting way of looking at history. I'm not sure if you have the right information. From what I gleamed from your other recent postings, you finally received the David Ehrlinger Cincinnati Zoo history book. If you read page 85 carefully, you will find that the enclosure in question was built in 1962 for baboons. I'm sure you realize that there were other Cincinnati zoo maps prior to 1993 that will have the baboon island on it.
As for the later renovations of the exhibit. I do know that it existed as baboon island as late as 1988. And that it held ibex as early as 1993. So the renovation occurred between 1988 and 1993. I do not have any information regarding when it was renovated for the lemurs (probably late 1990s?).
Okay, yep read it but on page 124, its says...
June 1962: Ibex Island (originally Baboon Island) completed near the Ape House at a cost of $77,000.
So this is indicating that Baboon Island was being renovated into Ibex Island in 1962. Did you know the island also held markhors? I can't find any other maps between 1962 and 1993, do you have any?