Paleognathae is a clade of birds that includes species such as ostriches, emus, and kiwis. These birds are characterized by their flat breastbones and a unique structure of their skulls, which distinguishes them from other bird groups. Paleognathae are primarily flightless and are found in various regions around the world, particularly in New Zealand, Australia, and Africa. Paleognathae are considered to be one of the most ancient lineages of birds, with a lineage that dates back to the time of the dinosaurs. They are typically large, ground-dwelling birds that have adapted to their environments in unique ways, such as developing strong legs for running and foraging for food.