Notopalaeognathae

Moa (order Dinornithiformes) are an extinct group of flightless birds formerly endemic to New Zealand. During the Late Pleistocene-Holocene, there were nine species, in six genera. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about in height with neck outstretched, and weighed about ; the smallest, the bush moa (Anomalopteryx didiformis), was about the size of a turkey. Estimates of the moa population when Polynesians settled New Zealand circa 1300 C.E. range from 58,000 to 2.5 million.

Tinamous () are members of the order Tinamiformes (), and family Tinamidae (), divided into two distinct subfamilies, containing 46 species found in Mexico, Central America, and South America. The word "tinamou" comes from the Galibi term for these birds, tinamu. Tinamous are the only living group of palaeognaths able to fly, and were traditionally regarded as the sister group of the flightless ratites, but recent work places them well within the ratite radiation as most closely related to the extinct moa of New Zealand, implying flightlessness emerged among ratites multiple times. Tinamous fi

Rheiformes is an order that contains the family Rheidae (rheas). It is in the infraclass Paleognathae, which contains all ratites. Extant members are found in South America. While the IOC World Bird List and the Clements Checklist categorise Rheiformes as its own order, the BirdLife Data Zone includes rheas, along with ostriches, tinamous, cassowaries, emu, and kiwis, in the order Struthioniformes. Of the two extant species of rheas recognized by the IUCN Red List, , Rhea americana is listed as near threatened, while Rhea pennata is listed as least concern. From 2014 to 2022, the IUCN recognis

Notopalaeognathae is a clade that contains the order Rheiformes (rheas), the clade Novaeratitae (which includes the cassowaries and emus, the kiwis, and the extinct elephant birds), and the clade Dinocrypturi (comprising the tinamous and the extinct moas). Notopalaeognathae was named by Yuri et al. (2013) and defined in the PhyloCode by Sangster et al. (2022) as "the least inclusive crown clade containing Rhea americana, Tinamus major, and Apteryx australis". The exact relationships of this group, including its recently extinct members, have only recently been uncovered. The two lineages endem

Lithornithidae is an extinct, possibly paraphyletic (but see below) group of early paleognath birds. They are known from fossils dating to the Upper Paleocene through the Middle Eocene of North America and Europe, with possible Late Cretaceous representatives. All are extinct today; the youngest specimen is the currently unnamed SGPIMH MEV1 specimen from the mid-Eocene Messel Pit site.

Novaeratitae is a clade that was originally defined to contain the recent common ancestors of the orders Casuariiformes (emus and cassowaries) and Apterygiformes (kiwi). This clade was named by Yuri et al. (2013) and phylogenetically defined in the PhyloCode by Sangster et al. (2022) as "the least inclusive crown clade containing Apteryx australis and Casuarius casuarius". Recently it has been determined that the elephant birds of the extinct order Aepyornithiformes were the closest relatives of the kiwis, and therefore are part of this group. The implication is that ratites had lost flight in