Struthionidae (; ) is a family of

flightless bird Flightless birds are birds that cannot Bird flight, fly, as they have, through evolution, lost the ability to. There are over 60 extant species, including the well-known ratites (ostriches, emus, cassowary, cassowaries, Rhea (bird), rheas, an ...

s, containing the extant

ostrich Ostriches are large flightless birds. Two living species are recognised, the common ostrich, native to large parts of sub-Saharan Africa, and the Somali ostrich, native to the Horn of Africa. They are the heaviest and largest living birds, w ...

es and their extinct relatives. The two extant species of ostrich are the

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

and

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 previou ...

, both in the genus '' Struthio'', which also contains several species known from

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

fossils such as the Asian ostrich. The common ostrich is the more widespread of the two living species, and is the largest living bird species. The extinct 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, Greece Crimea, Georgia (country), Georgia, and China. The genus contains three species: ...

'' from the Late Pliocene-Early Pleistocene of Eurasia is one of the largest birds ever. The first species of ''Struthio'' appear during the

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 ...

epoch, though various

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

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

, and

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

fossils may also belong to the family.Agnolin et al, Unexpected diversity of ratites (Aves, Palaeognathae) in the early Cenozoic of South America: palaeobiogeographical implications Article in Alcheringa An Australasian Journal of Palaeontology · July 2016 DOI: 10.1080/03115518.2016.1184898 Ostriches are classified in the

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

group of birds, all extant species of which are flightless, including the kiwis,

emu The emu (; ''Dromaius novaehollandiae'') is a species of flightless bird endemism, endemic to Australia, where it is the Tallest extant birds, tallest native bird. It is the only extant taxon, extant member of the genus ''Dromaius'' and the ...

s, and rheas. Traditionally, the order Struthioniformes contained all the ratites. However, recent genetic analysis has found that the group is not monophyletic, as it is paraphyletic with respect to the

tinamou Tinamous () are members of the order Tinamiformes (), and family Tinamidae (), divided into two distinct subfamily, subfamilies, containing 46 species found in Mexico, Central America, and South America. The word "tinamou" comes from the Carib la ...

s, so the ostriches are usually classified as the only members of the order, though the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

uses a broader classification and includes all "ratites" and tinamous in Struthioniformes.

Evolution

Struthionidae is a member of the

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, incl ...

, a group of paleognath birds which first appeared during the Early

, 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 (geology), epoch in the geologic time scale that extends from 5.33 to 2.58 The oldest records of Struthionidae, belonging to the genus '' Struthio'', are from the Early

of Africa, around 21 million years old. ''Struthio'' dispersed into and became widespread in Eurasia during the late middle-

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

epoch beginning around 12 million years ago. ''

'' from the Late Pliocene of Eurasia contains some of the largest bird species ever with some species likely weighing up to . Ostrich Ngorongoro 02

While the relationship of the African fossil species is comparatively straightforward, many Asian species of ostriches have been described from fragmentary remains, and their interrelationships and how they relate to the African ostriches are confusing. In

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, 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 there on prehistoric pottery and

petroglyph A petroglyph is an image created by removing part of a rock surface by incising, picking, carving, or abrading, as a form of rock art. Outside North America, scholars often use terms such as "carving", "engraving", or other descriptions ...

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. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

, 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) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...

s and the

Sahel The Sahel region (; ), or Sahelian acacia savanna, is a Biogeography, biogeographical region in Africa. It is the Ecotone, transition zone between the more humid Sudanian savannas to its south and the drier Sahara to the north. The Sahel has a ...

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

occurs in the

Horn of Africa The Horn of Africa (HoA), also known as the Somali Peninsula, is a large peninsula and geopolitical region in East Africa.Robert Stock, ''Africa South of the Sahara, Second Edition: A Geographical Interpretation'', (The Guilford Press; 2004), ...

, having evolved isolated from the common ostrich by the geographic barrier of the

East African Rift The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a l ...

. 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 ostrich The Arabian ostrich (''Struthio camelus syriacus''), Syrian ostrich, or Middle Eastern ostrich is an extinct subspecies of the ostrich that lived on the Arabian Peninsula and in the Near East until the mid-20th century. Distribution The Arabia ...

es in

Asia Minor Anatolia (), also known as Asia Minor, is a peninsula in West Asia that makes up the majority of the land area of Turkey. It is the westernmost protrusion of Asia and is geographically bounded by the Mediterranean Sea to the south, the Aegean ...

and

Arabia The Arabian Peninsula (, , or , , ) or Arabia, is a peninsula in West Asia, situated north-east of Africa on the Arabian plate. At , comparable in size to India, the Arabian Peninsula is the largest peninsula in the world. Geographically, the ...

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

Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

attempts to introduce North African ostriches 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 som ...

populations.Ostriches in Australia – and near my home
trevorsbirding.com (13 September 2007)

Taxonomy

In 2019, the species ''S. pannonicus'', ''S. dmanisensis'' (the giant ostrich), and ''S. transcaucasicus'' were transferred to the genus ''

''. Order Struthioniformes Latham 1790 (ostriches) * Family Struthionidae Vigors 1825 ** Genus †''

'' (Kretzoi 1954) (Late Pliocene Pleistocene) ** Genus '' Struthio'' Linnaeus 1758 (Early Miocene – Recent)

References

{{Authority control Extant Paleocene first appearances Bird families Taxa named by Nicholas Aylward Vigors

Evolution

Distribution and habitat

Taxonomy

See also

References