| Rheiformes | |
|---|---|
|   | |
| Greater rhea (Rhea americana) | |
| Scientific classification   | |
| Kingdom: | Animalia | 
| Phylum: | Chordata | 
| Class: | Aves | 
| Infraclass: | Palaeognathae | 
| Clade: | Notopalaeognathae | 
| Order: | Rheiformes Forbes, 1884 | 
| Families [2] | |
Rheiformes is an order that contains the family Rheidae (rheas). [3] 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, [3] [4] the BirdLife Data Zone includes rheas, along with ostriches, tinamous, cassowaries, emu, and kiwis, in the order Struthioniformes. [5] Of the two extant species of rheas recognized by the IUCN Red List, as of 2022 [update] , Rhea americana is listed as near threatened, [6] while Rhea pennata is listed as least concern. [7] From 2014 to 2022, the IUCN recognised Rhea tarapacensis as a separate species, and listed it as near threatened in its last assessment in 2020; [8] in 2022, it was again recognised as a subspecies of R. pennata. [7] : Taxonomy