Rheiformes

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}

Rheiformes Temporal range: Eocene – Holocene,[1] 40–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Greater rhea (Rhea americana)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Infraclass:	Palaeognathae
Clade:	Notopalaeognathae
Order:	Rheiformes Forbes, 1884
Families[2]
Rheidae †Opistodactylidae

References

1. Kirwan, Guy M.; Korthals, Arne; Hodes, Carly E. (2 April 2021). "Greater Rhea (Rhea americana), version 2.0". In Keeney, B. K. (ed.). Birds of the World. Ithaca, New York, United States: Cornell Lab of Ornithology. doi:10.2173/bow.grerhe1.02.
2. "Rheiformes". Global Biodiversity Information Facility. Retrieved 30 November 2022.
3. Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (11 August 2022). "Ratites: Ostriches to tinamous". IOC World Bird List (version 12.2 ed.). Retrieved 29 November 2022.
4. Clements, James F.; Schulenberg, Thomas S.; Iliff, Marshall J.; Fredericks, Thomas A.; Gerbracht, Jeff A.; LePage, Denis; Billerman, Shawn M.; Sullivan, Brian L.; Wood, Christopher L. (25 October 2022). "The eBird/Clements checklist of Birds of the World" (v2022 ed.). Ithaca, New York, United States: Cornell Lab of Ornithology. Retrieved 29 November 2022.
5. "HBW and BirdLife Taxonomic Checklist". BirdLife Data Zone (version 6.0b ed.). BirdLife International. July 2022. Retrieved 29 November 2022.
6. BirdLife International. (2022). "Rhea americana". IUCN Red List of Threatened Species. 2022: e.T22678073A219615764. doi:10.2305/IUCN.UK.2022-2.RLTS.T22678073A219615764.en. Retrieved 7 July 2024.
7. BirdLife International. (2022). "Rhea pennata". IUCN Red List of Threatened Species. 2022: e.T22678081A217016710. doi:10.2305/IUCN.UK.2022-2.RLTS.T22678081A217016710.en. Retrieved 7 July 2024.
8. BirdLife International. (2020). "Rhea tarapacensis". IUCN Red List of Threatened Species. 2020: e.T22728206A177987446. doi:10.2305/IUCN.UK.2020-3.RLTS.T22728206A177987446.en. Retrieved 7 July 2024.