Euornithes (from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

' meaning "true birds") is a natural group which includes the most recent common ancestor of all

avialan Avialae ("bird wings") is a clade containing the only living dinosaurs, the birds, and their closest relatives. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to deinonychosaurs, though alternative defi ...

s closer to modern

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s than to the enantiornithines. This group was defined in the ''

PhyloCode The ''International Code of Phylogenetic Nomenclature'', known as the ''PhyloCode'' for short, is a formal set of rules governing phylogenetic nomenclature. Its current version is specifically designed to regulate the naming of clades, leaving the ...

'' by Juan Benito and colleagues in 2022 as "the largest clade containing '' Vultur gryphus'', but not '' Enantiornis leali'' and '' Cathayornis yandica''".

Description

Clarke ''et al''. (2006) found that the most primitive known euornithians (the Yanornithiformes) had a mosaic of advanced and primitive features. These species retained primitive features like

gastralia Gastralia (: gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods. They are found between the sternum and pelvis, and do not articulate with the vertebrae. In these reptil ...

and a

pubic symphysis The pubic symphysis (: symphyses) is a secondary cartilaginous joint between the left and right superior rami of the pubis of the hip bones. It is in front of and below the urinary bladder. In males, the suspensory ligament of the penis attache ...

. They also showed the first fully modern

pygostyle Pygostyle is a skeletal condition in which the final few caudal vertebrae are fused into a single ossification, supporting the tail feathers and musculature. In modern birds, the rectrices attach to these. The pygostyle is the main component o ...

s, and the type specimen of ''

Yixianornis ''Yixianornis'' (meaning "Yixian Formation bird") is a bird genus from the early Cretaceous period. Its remains have been found in the Jiufotang Formation at Chaoyang, Liaoning, Chaoyang (People's Republic of China) dated to the early Aptian age, ...

'' (IVPP 13631) preserves eight elongated

rectrices Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the Bird wing, wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those ...

(tail feathers) in a modern arrangement. No earlier pygostylians are known which preserve a fan of tail feathers of this sort; instead, they showed only paired plumes or a tuft of short feathers.

Classification

The name Euornithes has been used for a wide variety of avialan groups since it was first named by

Leonhard Stejneger Leonhard Hess Stejneger (30 October 1851 – 28 February 1943) was a Norwegian-born American ornithologist, herpetologist and zoologist. Stejneger specialized in vertebrate natural history studies. He gained his greatest reputation with repti ...

in 1884. It was first defined as a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

in 1998 by

Paul Sereno Paul Callistus Sereno (born October 11, 1957) is a professor of paleontology at the University of Chicago who has discovered several new dinosaur species on several continents, including at sites in Inner Mongolia, Argentina, Morocco and Niger. ...

, who made it the group of all animals closer to birds than to

Enantiornithes The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct Avialae, avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teet ...

(represented by ''Sinornis''). This definition currently includes similar content as another widely used name, Ornithuromorpha, named and defined by

Luis Chiappe Luis María Chiappe (born 18 June 1962) is an Argentine paleontologist born in Buenos Aires who is best known for his discovery of the first sauropod nesting sites in the badlands of Patagonia in 1997 and for his work on the origin and early evol ...

in 1999 as the common ancestor of ''

Patagopteryx ''Patagopteryx'' is an extinct monotypic genus of euornithean dinosaurs that lived during the Late Cretaceous, around 80 mya (unit), mya, in what is now the Sierra Barrosa in northwestern Patagonia, Argentina. About the size of a chicken, it is t ...

'', '' Vorona'', and

Ornithurae Ornithurae (meaning "bird tails" in Greek) is a natural group that includes modern birds and their very close relatives such as the ichthyornithines and the hesperornithines. This clade is defined in the ''PhyloCode'' by Juan Benito and collea ...

, plus all of its descendants. Because one definition is node-based and the other branch-based, Ornithuromorpha is a slightly less inclusive group.

Relationships

The cladogram below follows the results of a phylogenetic analysis by Lee ''et al.'', 2014: The following cladogram below follows the results of a phylogenetic analysis by Pei ''et al.'', 2020:

Other genera

The following is a list of primitive euornithian genera and those that cannot be confidently referred to any subgroups, following Holtz (2011) unless otherwise noted.Holtz, Thomas R. Jr. (2012) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'
Winter 2011 Appendix.
/ref> *†'' Alamitornis'' *†'' Changmaornis'' *†'' Changzuiornis''Huang, J., Wang, X., Hu, Y., Liu, J., Peteya, J. A., & Clarke, J. A. (2016). A new ornithurine from the Early Cretaceous of China sheds light on the evolution of early ecological and cranial diversity in birds. ''PeerJ'', 4: e1765. *†'' Dingavis'' *†'' Gargantuavis'' *†'' Horezmavis'' *†'' Iteravis'' *†'' Juehuaornis'' *†'' Platanavis'' *†'' Wyleyia''? *†'' Yumenornis'' *'' Xinghaiornis'' *†'' Zhyraornis'' Note that Holtz also included the genera '' Eurolimnornis'' and '' Piksi'' as euornitheans, though they have since been re-identified as

pterosaur Pterosaurs are an extinct clade of flying reptiles in the order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 million to 66 million years ago). Pterosaurs are the earli ...

References

External links

{{Taxonbar, from=Q2752642 Bird clades