Zoo Tycoon 2: Extinct Animals is the fourth expansion to Zoo Tycoon 2. As the title indicates, it offers the possibility to add animals to your zoo that are extinct in real life. These animals are not simply for sale, you'll have to dig for fossils on the terrain of an existing or new zoo (with an upgradeable fossil detector), and bring them to life in your lab with a few mini-games. First you'll have to put the fossils together like a jigsaw puzzle. In a push-the-right-button-at-the-right-time mini-game you can then determine the strength and health of your new creation. The complexity of the jigsaw puzzles and the mini-game gradually increases.
The expansion adds 34 animals, from dodo and American mastodon to saber-toothed cat, Stegosaurus and Tyrannosaurus Rex to the zoo catalogue. Most animals can live together with today's species peacefully, but carnivorous dino's will eat your other animals if you're not careful. Some extinct animals can break free from their cages, which causes a panic among the visitors and can create a lot of damage. You can either tranquillize them yourself in a mini-game as soon as this happens or hire a team to do it for you. The formerly extinct animals can also get ill. By taking samples of their surroundings you can find a cure.
The game also adds new buildings, objects, staff members and challenges. Most of them are unlocked by finishing certain campaigns.