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 lightweigh ...

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 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,

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 (biology), order containing a considerable number of living and extinct bird family (biology), families, with a widespread geographical diversity. Gruiform means "crane-like". Traditionally, a number of wading and t ...

, 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 ph ...

, 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. 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), owls ...

(

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 widespread ...

s plus Accipitriformes, and owls) are also predatory, it is inferred that the common ancestor of 'core landbirds' ( Telluraves) was an apex predator. However, some researchers like Darren Naish 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 (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

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 have ...

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 with ...

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 contine ...

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 th ...

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''. 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