Casuariidae Casuariidae The bird family Casuariidae has four surviving members: the three species of cassowary and the emu. All living members of the family are very large flightless birds native to Australia-New Guinea, though the extinct potential member "Hypselornis" was native to India. The characteristics of the family are those of its members. The fossil record of casuariforms is interesting, but not very extensive. Some Australian fossils initially believed to be from emus were recognized to represent a distinct genus, "Emuarius", which had a cassowary-like skull and femur and an emu-like lower leg and foot. A Pliocene Indian ratite, "Hypselornis", has
Flightless bird requirement for flightlessness. The kiwi does not exhibit gigantism, along with tinamous, even though they coexisted with the moa and rhea that both exhibit gigantism. This could be the result of different ancestral flighted birds arrival or because of competitive exclusion. The first flightless bird to arrive in each environment utilized the large flightless herbivore or omnivore niche, forcing the later arrivals to remain smaller. In environments where flightless birds are not present, it is possible that after the K/T Boundary there were no niches for them to fill. They were pushed out by other herbivorous mammals. New Zealand had