From the publisher's website: This expansion set for the American Megafauna evolutionary game adds new technology, venom, and marine adaptations. It also expands the game into a five-player game, with the addition of the Proto-Croc player, aka “Arizonasaurus”. This is an expansion set, you will need American Megafauna to play, preferably the second edition. Expansion set contents: A booklet that includes errata, alternate starting biomes, and a personal commentary on the significance of the game to today’s events, A new creature sheet, along with a card and tents for the new fifth player, New cards: 31 new DNA cards, 9 new biome cards, 4 new catastrophe cards, and 2 new genotype cards. Expands: American Megafauna