After spending the night at an old man's antique shop with Julia, Winston falls in love with the idea of having a place all alone to himself where no one could tell him what to do. No one could watch him or punish him. He finally felt free, if only just for a few hours every now and again. The metaphor he uses for this room was undoubtedly the best way to describe the experiences it gave him. It shows that it is everything Winston desires to have in his life once again. The "extinct animals" refer to all the people living in such totalitarianism. It shows that at one time, these "animals" were alive and thriving. But they became "extinct" as time went on and they had their lives taken away from them by dictators who gained total control over them. To Winston, being the "extinct" animal that he was, this new world where he could "walk" again or be free was the ultimate dream and desire that he wished for all people.