Ostriches are large

flightless Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species, including the well known ratites (ostriches, emu, cassowaries, rheas, and kiwi) and penguins. The smallest flightless bird is the ...

birds of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Struthio'' in the order

Struthioniformes Struthioniformes is an order of birds with only a single extant family, Struthionidae, containing the ostriches. Several other extinct families are known, spanning across the Northern Hemisphere, from the Early Eocene to the early Pliocene, includ ...

, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the

emu The emu () (''Dromaius novaehollandiae'') is the second-tallest living bird after its ratite relative the ostrich. It is endemic to Australia where it is the largest native bird and the only extant member of the genus '' Dromaius''. The emu ...

s, rheas, and

kiwi Kiwi most commonly refers to: * Kiwi (bird), a flightless bird native to New Zealand * Kiwi (nickname), a nickname for New Zealanders * Kiwifruit, an edible berry * Kiwi dollar or New Zealand dollar, a unit of currency Kiwi or KIWI may also ref ...

s. There are two living species of ostrich: the

common ostrich The common ostrich (''Struthio camelus''), or simply ostrich, is a species of flightless bird native to certain large areas of Africa and is the largest living bird species. It is one of two extant species of ostriches, the only living members o ...

, native to large areas of sub-Saharan Africa and the

Somali ostrich The Somali ostrich (''Struthio molybdophanes''), also known as the blue-necked ostrich, is a large flightless bird native to the Horn of Africa. It is one of two living species of ostriches, the other being the common ostrich. It was also previo ...

, native to the Horn of Africa. The common ostrich was also historically native to the Arabian Peninsula, and ostriches were present across Asia as far east as Mongolia during the Late Pleistocene and possibly into the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

. They lay the largest eggs of any living land animal. With the ability to run at 70 km/h (43.5 mph), they are the fastest birds on land. They are farmed worldwide, particularly for their feathers as they are used as decoration and feather dusters. Their skin is also used for leather products. They are the heaviest living birds.

Taxonomic history

The genus ''Struthio'' was first described by

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...

in 1758. The genus was used by Linnaeus and other early taxonomists to include the

, rhea, and

cassowary Cassowaries ( tpi, muruk, id, kasuari) are flightless birds of the genus ''Casuarius'' in the order Casuariiformes. They are classified as ratites (flightless birds without a keel on their sternum bones) and are native to the tropical fore ...

, until they each were placed in their own genera. The Somali ostrich (''Struthio molybdophanes'') has recently become recognized as a separate species by most authorities, while others are still reviewing the evidence.Birdlife International (2012)

Evolution

Struthionidae is a member of the

, a group of

paleognath Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contain ...

birds which first appeared during the Early

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

, and includes a variety of flightless forms which were present across the Northern Hemisphere (Europe, Asia and North America) during the Eocene epoch. The closest relatives of Struthionidae within the Struthioniformes are the Ergilornithidae, known from the late Eocene to early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 The earliest fossils of the genus ''Struthio'' are from the early

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

~21 million years ago of Namibia in Africa, so it is proposed that genus is of African origin. By the middle to late

(5–13 mya) they had spread to and become widespread across Eurasia. While the relationship of the African fossil species is comparatively straightforward, many Asian species of ostrich have been described from fragmentary remains, and their interrelationships and how they relate to the African ostriches are confusing. In India, Mongolia and China, ostriches are known to have become extinct only around, or even after, the end of the last ice age; images of ostriches have been found prehistoric Chinese pottery and petroglyphs. File: Struthio camelus MHNT.ZOO.2010.11.1.1.jpg, ''Struthio camelus'' egg – MHNT File:Ostrich & chicken egg comparison.jpg, Size comparison (with a chicken egg and a US dollar bill) File:Ostrich with eggs.jpg, Ostrich with eggs

Distribution and habitat

Today, ostriches are only found natively in the wild in

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

, where they occur in a range of open arid and semi-arid habitats such as

savanna A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...

s and the Sahel, both north and south of the equatorial forest zone. The

occurs in the Horn of Africa, having evolved isolated from the common ostrich by the geographic barrier of the East African Rift. In some areas, the common ostrich's Masai subspecies occurs alongside the Somali ostrich, but they are kept from interbreeding by behavioral and ecological differences. The Arabian ostriches in

Asia Minor Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...

and

Arabia The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plat ...

were hunted to extinction by the middle of the 20th century, and in

Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...

attempts to introduce

North African ostrich The North African ostrich, red-necked ostrich, or Barbary ostrich (''Struthio camelus camelus'') is the nominate subspecies of the common ostrich from West and North Africa. It is the largest subspecies, making it the largest living bird. Evolu ...

es to fill their ecological role have failed. Escaped common ostriches in Australia have established

feral A feral () animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in some ...

populations.

Species

In 2008, ''S. linxiaensis'' was transferred to the genus '' Orientornis.'' Three additional species, ''S. pannonicus'', ''S. dmanisensis'', and ''S. transcaucasicus'', were transferred to the genus ''

Pachystruthio ''Pachystruthio'' is a genus of extinct bird which lived in Eurasia from the Late Pliocene to the Middle Pleistocene. Its fossils have been found in Hungary, the Crimea, Romania, Georgia, and China. The genus contains three species: ''P. pannonic ...

'' in 2019. Several additional fossil forms are

ichnotaxa An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxa'' comes from the Greek ίχνος, ''ichnos'' meaning ''track'' and ταξις, ''taxis'' meaning ...

(that is, classified according to the organism's

trace fossil A trace fossil, also known as an ichnofossil (; from el, ἴχνος ''ikhnos'' "trace, track"), is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils, ...

s such as footprints rather than its body) and their association with those described from distinctive bones is contentious and in need of revision pending more good material. The species are: *Prehistoric ** †''

Struthio barbarus Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There a ...

'' Arambourg 1979 ** †''

Struthio brachydactylus Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There a ...

'' Burchak-Abramovich 1939 (Pliocene of Ukraine) ** †'' Struthio chersonensis'' (Brandt 1873) Lambrecht 1921 (Pliocene of SE Europe to WC Asia) – oospecies ** †'' Struthio coppensi'' Mourer-Chauviré et al. 1996 (Early Miocene of Elizabethfeld, Namibia) ** †'' Struthio daberasensis'' Pickford, Senut & Dauphin 1995 (Early – Middle Pliocene of Namibia) – oospecies ** †'' Struthio epoasticus'' Bonaparte 1856 ** †'' Struthio kakesiensis'' Harrison & Msuya 2005 (Early Pliocene of Laetoli, Tanzania) – oospecies ** †''

Struthio karingarabensis Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There a ...

'' Senut, Dauphin & Pickford 1998 (Late Miocene – Early Pliocene of SW and CE Africa) –

oospecies Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg may preserve the remains of ...

(?) ** †'' Struthio oldawayi'' Lowe 1933 (Late Pleistocene of Tanzania) – probably subspecies of ''S. camelus'' ** †'' Struthio orlovi'' Kuročkin & Lungo 1970 (Late Miocene of Moldavia) ** †''

Struthio wimani ''Struthio wimani'' is an extinct species of ratite bird from the Pliocene of China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, mo ...

'' Lowe 1931 (Early Pliocene of China and Mongolia) * Late Pleistocene

** †''

Struthio anderssoni Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There a ...

'' Lowe 1931, East Asian ostrich (Late Pleistocene of China to Mongolia)J. G. Andersson, Essays on the cenozoic of northern China. ''Memoirs of the Geological Survey of China (Peking)'', Series A, No. 3 (1923), pp. 1–152, especially pp. 53–77: "On the occurrence of fossil remains of Struthionidae in China."; and J. G. Andersson, Research into the prehistory of the Chinese. Bulletin of the Museum of Far Eastern Antiquities 15 (1943), 1–300, plus 200 plates. oospecies(?) ** †'' Struthio asiaticus'' Brodkorb 1863,

Asian ostrich The Asian or Asiatic ostrich (''Struthio asiaticus''), is an extinct species of ostrich that lived during the Neogene period on the Indian subcontinent. The early records that ranged from the Pliocene epoch in Africa to Pleistocene-Holocene epoc ...

(Early Pliocene – Early Holocene of Central Asia to China? and Morocco) ** ''

Struthio camelus The common ostrich (''Struthio camelus''), or simply ostrich, is a species of flightless bird native to certain large areas of Africa and is the largest living bird species. It is one of two extant species of ostriches, the only living members o ...

'',

*** '' Struthio camelus camelus'',

*** '' Struthio camelus massaicus'', Masai ostrich *** '' Struthio camelus australis'', South African ostrich *** †'' Struthio camelus syriacus'', Arabian ostrich ** '' Struthio molybdophanes'',

Citations

General references

* * * * * * * * * * {{Authority control Extant Miocene first appearances Flightless birds Miocene birds Ratites Taxa named by Carl Linnaeus