Geography of New Caledonia a refugium, in effect a biological "Noah's Ark", an island home to both unique living plants and animals and also to its own special fossil endowment. Birds such as the crested and almost flightless kagu (French, "cagou") "Rhynochetos jubatus", whose closest relative may be the distantly related sunbittern of South America, and plants such as "Amborella trichopoda", the only known member of the most basal living branch of flowering plants, make this island a treasure trove and a critical concern for biologists and conservationists. The island was home to horned fossil turtles ("Meiolania mackayi") and terrestrial fossil crocodiles ("Mekosuchus inexpectatus")
Kagu gruiform, the kagu is generally considered related to the extinct adzebills from New Zealand and the sunbittern from Central and South America. Recent studies do indicate that the sunbittern is the closest living relative of the kagu. For example, Fain & Houde found these to be certainly sister taxa. They and the mesites did not group with traditional Gruiformes in their study, but instead with their proposed clade Metaves, which also includes the hoatzin, pigeons, Caprimulgiformes, flamingos, tropicbirds, Apodiformes, sandgrouse and grebes. The internal structure of this group was not well resolvable by their data, although later studies confirmed a