This is a small order with some very remarkable birds in it. It includes 5 families all of which were until recently given ordinal status in their own right, however, modern DNA information and cladistic analyses have brought them all together in one order. These five families are called Ratites and are all flightless birds without a keeled breastbone. They are all primarily herbivorous to omnivorous.
Other things that all members of the order have in common are nesting on the ground and incubation of the eggs mostly or entirely by the male.