Papua New Guinea notable feature in common for the two landmasses is the existence of several species of marsupial mammals, including some kangaroos and possums, which are not found elsewhere. Papua New Guinea is a megadiverse country. Many of the other islands within PNG territory, including New Britain, New Ireland, Bougainville, the Admiralty Islands, the Trobriand Islands, and the Louisiade Archipelago, were never linked to New Guinea by land bridges. As a consequence, they have their own flora and fauna; in particular, they lack many of the land mammals and flightless birds that are common to New Guinea and Australia. Australia and New
Herding dog conformation shows they usually form a separate group. Australia has the world's largest cattle stations and sheep stations and some of the best-known herding dogs, such as the Koolie, Kelpie, Red and Blue Heelers are bred and found there. The competitive dog sport in which herding dogs move animals around a field, fences, gates, or enclosures as directed by their handlers is called a "sheepdog trial", "herding test" or "stockdog trial" depending on the area. Such events are particularly associated with hill farming areas, where sheep range widely on largely unfenced land. These trials are popular in the United Kingdom,