Bulldog rat

The bulldog rat (Rattus nativitatis) is an extinct rat that was endemic to Christmas Island in the Indian Ocean, where it shared the island with one other native rat, Maclear's rat. It was large for a rat, with a head and body about 25 to 27 centimetres long, an estimated weight of 250 to 300 grams, a short thick tail and coarse dark reddish-brown hair; its back carried a layer of fat about two centimetres thick. It lived in the higher hills and denser forest in small colonies, in burrows among tree roots or under the hollow logs of sago palms, and was sluggish, never climbed and was strictly nocturnal. The last record dates from 1903. Mass die-offs around 1902 and 1903 are thought to reflect a disease brought by black rats that sailors had accidentally introduced. Though long placed in Rattus, it is now thought to nest within Bunomys, a genus of Sulawesi and nearby islands.