Living species of Paleognathae, the ancestral-most group of birds, are the African Ostrich, the Australian Emu, three species of Kassowaries, two species of Rheas and five species of Kiwis. These flightless birds display a near-complete absence of featherless areas in the skin, and most often, a dark grey-to-brown homogeneous plumage. Juveniles show sharp grey and white longitudinal stripes of varying sizes and location along the antero-posterior axis.
Juveniles show sharp grey and various periodic color patterns, including dotted motifs along the ostrich's chick neck or white longitudinal stripes of varying sizes and location along the antero-posterior axis in the emu juvenile.
Ratites breed well in captivity and fertilized eggs can be obtained from local suplliers. While the embryonic development is long, the large size of eggs and embryonic specimens facilitates phenotypic description and manipulation.