Zoo Tycoon 2 - Extinct Animals

Quagga:
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Release all extinct animals into the wild to unlock the Quagga.

Lab accident animals:
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Get an animal creation mini-game score lower than 50\% to
unlock one of the following animals:

Giant Bullfrog
Giant Monarch Butterfly
Killer Penguin
Red Squirrel
Springhare

Note:
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Except for the Killer Penguin, all of these animals are just
selectable ambients.