Bramble Cay Melomys

Melomys rubicola was relatively large for a rodent, with a body-length ranging from 14.8 to 16.5 centimetres (5+7⁄8 to 6+1⁄2 in) and a tail-length between 14.5 and 18.5 centimetres (5+3⁄4 and 7+1⁄4 in). Compared to other rats, it had a long tail, short ears, and large feet. Its weight was recorded as between 78 and 164 grams (2+3⁄4 and 5+3⁄4 oz). The tail was prehensile at the tip and covered with rough scales. The fur was reddish brown above and greyish brown below, with black guard hairs on its back. It was similar in appearance to the Cape York melomys, to which it was closely related. As with other species of melomys, it was described as having a Roman nose.

Scientists are uncertain on how the animal reached Bramble Cay. Studies have theorized that it either reached Bramble Cay from the island of New Guinea by floating on driftwood, or that it reached the region when it was still above water at a time when Australia was connected to New Guinea by a land bridge, and then persisted into recent times. The Bramble Cay melomys was described in 2002 as Australia's most isolated mammal. The cay is located in the northeastern portion of the Torres Strait, approximately 50 kilometres (31 mi) from the mouth of the Fly River in Papua New Guinea. The cay is between 4 and 5 hectares (9+7⁄8 and 12+3⁄8 acres), but the rodent only occupied the vegetated portion of the island, measuring approximately 2 hectares (5 acres). The vegetation of the island comprises grasses and herbs, generally shorter than 0.4 metres (1 ft 4 in). Although 11 species of plants have been recorded on the island in the past, only three to five species have been recorded as present at the same time. Common species include Portulaca oleracea, Boerhavia albiflora, Cenchrus echinatus, and Amaranthus viridis. Three species were observed in 1994: Amaranthus viridis, Boerhavia tetrandra (genus Boerhavia), a type of spinach eaten by humans; and Lepturus repens. …

Little is known of the diet, but it is suggested that melomys rats were primarily herbivorous, feeding on leaves, seeds, fruits and flowers. They were scansorial, adapted to climbing rainforest trees to search for food. Melomys were important prey items for many rainforest predators, such as sooty owls and pythons. The melomys had a varied diet, feeding on plant matter, insects, and possibly bird eggs. The ability to survive in a limited habitat with scarce resources showcased the resilience of the Bramble Cay species.

First Dog on the Moon published a cartoon tribute to the Bramble Cay melomys, entitled "A moment of silence for the Bramble Cay melomys, another victim of climate change", on 20 February 2019, and another to remember the anniversary of its extinction. In August 2021, a group of artists from Erub Island created a series of works called Maizab Kaur Mukeis (the Meriam Mir name for the Bramble Cay melomys), consisting of sculptures of the animal made with ghost nets. The work was inspired by the news of its extinction, with the artists hoping to create awareness of the damage caused by the abandoned fishing nets to marine ecosystems. The work was selected as one of four Queensland finalists for the National Aboriginal and Torres Strait Islander Art Awards (NATSIAA).