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 Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

families Phorusrhacidae,

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 terrest ...

, Idiornithidae and Ameghinornithidae. Though traditionally considered a suborder within Gruiformes, 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 inclu ...

, 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 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 widespr ...

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 lev ...

. 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'', '' Xenop ...

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

from the Cape Lamb Member of the Lopez de Bertodano Formation, Vega Island,

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 cont ...

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 seriemas, 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 ...

studies have shown that Cariamiformes is basal 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