Cariamiformes (or Cariamae) is an order of primarily flightless

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s that has existed for over 60 million years. The group includes the family Cariamidae (seriemas) and the extinct families

Phorusrhacidae Phorusrhacids, colloquially known as terror birds, are an extinct clade of large carnivorous flightless birds that were one of the largest species of apex predators in South America during the Cenozoic era; their conventionally accepted temporal ...

Bathornithidae Bathornithidae is an extinct family of birds from the Eocene to Miocene of North America. Part of Cariamiformes, they are related to the still extant seriemas and the also extinct Phorusrhacidae. They were likely similar in habits, being terre ...

Idiornithidae Idiornithidae is an extinct family of Cariamiformes. Fossils of these birds were found mainly in the phosphorus layers of Quercy in south-western France. Other specimens have been found throughout Germany as well. Description The Idiornithidae ...

and Ameghinornithidae. Though traditionally considered a suborder within

Gruiformes The Gruiformes are an order containing a considerable number of living and extinct bird families, with a widespread geographical diversity. Gruiform means "crane-like". Traditionally, a number of wading and terrestrial bird families that did n ...

, both morphological and genetic studies show that it belongs to a separate group of birds,

Australaves Australaves is a recently defined clade of birds, consisting of the Eufalconimorphae (passerines, parrots and falcons) as well as the Cariamiformes (including seriemas and the extinct "terror birds").Prum, R.O. ''et al''. (2015A comprehensive ...

, whose other living members are

Falconidae The falcons and caracaras are around 60 species of diurnal birds of prey that make up the family Falconidae (representing all extant species in the order Falconiformes). The family is divided into three subfamilies, Herpetotherinae, which incl ...

, Psittaciformes and

Passeriformes A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...

. This proposal has been confirmed by a 2014 study of whole genomes of 48 representative bird species. This analysis shows that the Cariamiformes are

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

among extant

, while falcons are next most basal; in combination with the fact that the two most basal branches of

Afroaves Afroaves is a clade of birds, consisting of the kingfishers and kin (Coraciiformes), woodpeckers and kin (Piciformes), hornbills and kin (Bucerotiformes), trogons ( Trogoniformes), cuckoo roller ( Leptosomiformes), mousebirds ( Coliiformes), owl ...

(

New World vulture The New World vulture or condor family, Cathartidae, contains seven extant species in five genera. It includes five extant vultures and two extant condors found in warm and temperate areas of the Americas. The "New World" vultures were widesprea ...

s plus

Accipitriformes The Accipitriformes (; from Latin ''accipiter''/''accipitri-'' "hawk", and New Latin ''-formes'' "having the form of") are an order of birds that includes most of the diurnal birds of prey, including hawks, eagles, vultures, and kites, but not f ...

, and

owl Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...

s) are also predatory, it is inferred that the common ancestor of 'core landbirds' (

Telluraves Telluraves (also called land birds or core landbirds) is a recently defined clade of birds defined by their arboreality. Based on most recent genetic studies, the clade unites a variety of bird groups, including the australavians (passerines, p ...

) was an

apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic le ...

. However, some researchers like

Darren Naish Darren William Naish is a British vertebrate palaeontologist, author and science communicator. As a researcher, he is best known for his work describing and reevaluating dinosaurs and other Mesozoic reptiles, including '' Eotyrannus'', ''Xeno ...

feel that this assessment is biased towards the more well known, predatory representatives of the clade, and indeed at least one form, ''

Strigogyps ''Strigogyps'' is an extinct genus of prehistoric bird from the Middle Eocene to Early Oligocene of France and Germany. It was probably around the size of a large chicken or a guan, weighing not quite . Apparently, as indicated by the ratio of l ...

'', appears to have been herbivorous. The earliest known unambiguous member of this group is 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'', " ...

taxon ''

Paleopsilopterus ''Paleopsilopterus'' is an extinct genus of giant flightless predatory birds within Cariamiformes. It is usually attributed to the subfamily Psilopterinae of the family Phorusrhacidae, or "terror birds", though doubts about such an identity hav ...

itaboraiensis''. An isolated

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

from the Cape Lamb Member of the

Lopez de Bertodano Formation The Lopez de Bertodano Formation is a geological formation in the James Ross archipelago of the Antarctic Peninsula. The strata date from the end of the Late Cretaceous (upper-lower Maastrichtian stage) to the Danian stage of the lower Paleocene, ...

Vega Island Vega Island is a small island to the northwest of James Ross Island, on the Antarctic Peninsula. It is separated from James Ross Island by Herbert Sound. The island was named by Otto Nordenskjold, leader of the Swedish Antarctic Expedition (190 ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest co ...

was briefly described as a cariamiform femur in 2006. This specimen, which dates to the late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

period 66 million years ago, was originally reported as indistinguishable from the femurs of modern

seriema The seriemas are the sole living members of the small bird family Cariamidae, which is also the only surviving lineage of the order Cariamiformes. Once believed to be related to cranes, they have been placed near the falcons, parrots and passerin ...

s, and belonging to a large bird about tall. Because of its age and geographic location, it was argued that this unnamed species may have been close to the ancestry of both cariamids and phorusrhacids. However, a subsequent study published by West ''et al.'' (2019) reinterpreted this specimen as a fossil of an unnamed large-bodied member of a non-cariamiform genus ''

Vegavis ''Vegavis'' is a genus of extinct bird that lived during the Late Cretaceous (Maastrichtian stage) of Antarctica, some 68 to 66 mya. Among modern birds, most studies show that ''Vegavis'' is most closely related to ducks and geese (Anatidae), b ...

''. Molecular

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

studies have shown that Cariamiformes is

to the Falconiformes, Psittaciformes and Passeriformes:

References

{{Taxonbar, from=Q1207101 Bird orders Extant Paleocene first appearances Paleocene taxonomic orders Eocene taxonomic orders Oligocene taxonomic orders Miocene taxonomic orders Pliocene taxonomic orders Pleistocene taxonomic orders Holocene taxonomic orders