Flightless bird more species of flightless birds (including the kiwi, several species of penguins, the takahe, the weka, the moa, and several other extinct species) than any other such location. One reason is that until the arrival of humans roughly a thousand years ago, there were no large land predators in New Zealand; the main predators of flightless birds were larger birds. Ratites belong to the superorder Palaeognathae birds, which include the volant tinamou, and are believed to have evolved flightlessness independently multiple times within their own group. Some birds evolved flightlessness in response to the absence of predators, for example on
Ratite as a whole probably had an origin in the northern hemisphere. Early Cenozoic northern hemisphere paleognaths such as "Lithornis", "Pseudocrypturus", "Paracathartes" and "Palaeotis" appear to be the most basal members of the clade. The various ratite lineages were probably descended from flying ancestors that colonised the south in multiple waves, probably initially in South America, and then evolved gigantism. Loss of flight allows birds to eliminate the energetic cost of maintaining flight-enabling pectoral muscle mass. The basal metabolic rate of volant species is much higher than that of flightless terrestrial birds. But energetic efficiency can only help explain the loss