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
Hesperornithes Hesperornithes Hesperornithes is an extinct and highly specialized group of aquatic avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genera such as "Hesperornis", "Parahesperornis", "Baptornis", "Enaliornis", and "Potamornis", all strong-swimming, predatory divers. Many of the species most specialized for swimming were completely flightless. The largest known hesperornithean, "Canadaga arctica", may have reached a maximum adult length of over . Hesperornitheans were the only Mesozoic avialans to colonize the oceans. They were wiped out in the Cretaceous–Paleogene extinction event, along with enantiornitheans and all other non-avian dinosaurs,