The Family Casuariidae includes large, flightless birds known as cassowaries and emus, native to Australia, New Guinea, and surrounding islands. Members of this family are ratites, meaning they have a flat breastbone without a keel, which prevents flight but supports strong leg muscles for running. Cassowaries are known for their vividly colored necks and helmet-like casques, while emus are more uniform in appearance. These birds are omnivorous, feeding on fruits, seeds, insects, and small animals, and play a key role in seed dispersal in their ecosystems. Casuariids are generally solitary or live in small groups and are notable for their speed, strength, and, in cassowaries, potentially dangerous defensive behavior.