Mervin the Missing Link

 was one of the missing links between reptiles and mammals. He was the last of his kind, and was kept in the Museum of the Last Ones. Dougal Dunnock wrote a definitive guide to his species based on incorrect theories. When Frank stole him, the professor bought him to save his reputation. Dougal took great care of him and offered him food, water, and a goldfish and a hamster for mating. He was later taken back to his own time by the Tenth Doctor. Spotting him was worth 23500 points in the I-Spyder Book of Earth Creatures. (PROSE: The Last Dodo)