into a gorilla pit. time seems to stand still, as the gorillas take notice. >> oh, my god. >> it's an elephant, see? >> it's august 16th, 1996. a small group of families is enjoying the zoo together in brookfield, illinois. >> how many are there? >> we had gone to the zoo, the three of us, our families. i was with my wife and my oldest daughter. taking some video of some of the monkeys in the trees. >> there he is. >> as usual, the gorillas are a big hit. their massive size, up to six feet, and more than 400 pounds, and their human-like behavior captivate kids and parents alike. >> we were on our way out of the park when we decided to stop in and see tropic world. >> look at the monkeys. >> look at them running. >> it was very crowded. >> once we got in there, we