Ratite

Ratites
Temporal range: Paleocene–Holocene 56–0 Ma Possible Late Cretaceous record
Members of the four genera of large extant ratites. Clockwise from top left: greater rhea, ostrich, southern cassowary and emu
Members of the four genera of large extant ratites. Clockwise from top left: greater rhea, ostrich, southern cassowary and emu
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Infraclass: Palaeognathae
Groups included
Cladistically included but traditionally excluded taxa

Tinamiformes

Synonyms

Ratites (/ˈrætaɪts/) are a polyphyletic group consisting of all birds within the infraclass Palaeognathae that lack keels and cannot fly.[3] They are mostly large, long-necked, and long-legged, the exception being the kiwi, which is also the only nocturnal extant ratite.

The understanding of relationships within the paleognath clade has been in flux. Previously, all the flightless members had been assigned to the order Struthioniformes, which is more recently regarded as containing only the ostrich.[4][5] The modern bird superorder Palaeognathae consists of ratites and the flighted Neotropic tinamous (compare to Neognathae).[6] Unlike other flightless birds, the ratites have no keel on their sternum — hence the name, from the Latin ratis ('raft', a vessel which has no keel — in contradistinction to extant flighted birds with a keel).[7] Without this to anchor their wing muscles, they could not have flown even if they had developed suitable wings.[citation needed] Ratites are a polyphyletic group; tinamous fall within them, and are the sister group of the extinct moa.[6][8][9][10] This implies that flightlessness is a trait that evolved independently multiple times in different ratite lineages.[9][11]

Most parts of the former supercontinent Gondwana have ratites, or did have until the fairly recent past.[12][13] So did Europe in the Paleocene and Eocene, from where the first flightless paleognaths are known.[14] Ostriches were present in Asia as recently as the Holocene, although the genus is thought to have originated in Africa.[15] However, the ostrich order may have evolved in Eurasia.[15] A recent study posits a Laurasian origin for the clade.[16] Geranoidids, which may have been ratites, existed in North America.[17]

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  2. ^ a b c d e f Cite error: The named reference Salvadori was invoked but never defined (see the help page).
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  6. ^ a b Cite error: The named reference Phillips2010 was invoked but never defined (see the help page).
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  9. ^ a b Cite error: The named reference Mitchell2014 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Baker2014 was invoked but never defined (see the help page).
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  12. ^ Cite error: The named reference Haddrath, O & Baker, A (2001) was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Cooper was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Buffetaut2014 was invoked but never defined (see the help page).
  15. ^ a b Cite error: The named reference Hou2014 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Yonezawa2017 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Mayr2019 was invoked but never defined (see the help page).