Euornithes (from Greek ευόρνιθες euórnithes meaning "true birds") is a natural group which includes the most recent common ancestor of all avialans closer to modern birds than to Sinornis.

Temporal range:
Early CretaceousPresent,[1] 130.7–0 Ma
Fossil specimen (DNHM D2945 6) of Hongshanornis longicresta
Fossil specimen of Hongshanornis longicresta
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Clade: Ornithothoraces
Clade: Euornithes
Cope, 1889

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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 (belly ribs) and a pubic symphysis. They also showed the first fully modern pygostyles, and the type specimen of Yixianornis (IVPP 13631) preserves eight elongated rectrices (tail feathers) in a modern arrangement. No earlier pygostylians are known which preserve a fan of tail feathers of this sort; instead, they show only paired plumes or a tuft of short feathers.[2]


The name Euornithes has been used for a wide variety of avialan groups since it was first named by Edward Drinker Cope in 1889. It was first defined as a clade in 1998 by Paul Sereno, who made it the group of all animals closer to birds than to Enantiornithes (represented by Sinornis). This definition currently includes similar content as another widely used name, Ornithuromorpha, named and defined by Luis Chiappe in 1999 as the common ancestor of Patagopteryx, Vorona, and Ornithurae, plus all of its descendants. Because one definition is node-based and the other branch-based, Ornithuromorpha is a slightly less inclusive group.


The cladogram below follows the results of a phylogenetic analysis by Lee et al., 2014:[3]






















Aves (modern birds)

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.[4]

Note that Holtz also included the genera Eurolimnornis and Piksi as euornitheans, though they have since been re-identified as pterosaurs.[7]


  1. ^ Min Wang; Xiaoting Zheng; Jingmai K. O’Connor; Graeme T. Lloyd; Xiaoli Wang; Yan Wang; Xiaomei Zhang; Zhonghe Zhou (2015). "The oldest record of Ornithuromorpha from the Early Cretaceous of China". Nature Communications. 6: Article number 6987. doi:10.1038/ncomms7987. PMC 5426517. PMID 25942493.
  2. ^ Clarke, Julia A.; Zhou, Zhonghe; Zhang, Fucheng (2006). "Insight into the evolution of avian flight from a new clade of Early Cretaceous ornithurines from China and the morphology of Yixianornis grabaui". Journal of Anatomy. 208 (3): 287–308. doi:10.1111/j.1469-7580.2006.00534.x. PMC 2100246. PMID 16533313.
  3. ^ Lee, Michael SY; Cau, Andrea; Darren, Naish; Gareth J., Dyke (2013). "Morphological Clocks in Paleontology, and a Mid-Cretaceous Origin of Crown Aves". Systematic Biology. 63 (3): 442–9. doi:10.1093/sysbio/syt110. PMID 24449041.
  4. ^ Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.
  5. ^ a b Wang, Y.-M.; et al. (2013). "Previously Unrecognized Ornithuromorph Bird Diversity in the Early Cretaceous Changma Basin, Gansu Province, Northwestern China". PLoS ONE. 8 (10): e77693. doi:10.1371/journal.pone.0077693. PMC 3795672. PMID 24147058.
  6. ^ a b c d e 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. doi:10.7717/peerj.1765
  7. ^ Federico L. Agnolin; David Varricchio (2012). "Systematic reinterpretation of Piksi barbarulna Varricchio, 2002 from the Two Medicine Formation (Upper Cretaceous) of Western USA (Montana) as a pterosaur rather than a bird". Geodiversitas. 34 (4): 883–894. doi:10.5252/g2012n4a10. Archived from the original on 2013-01-07.

External links

Media related to Euornithes fossils at Wikimedia Commons


Ambiortiformes is a group of prehistoric birds.

The first species to be included, Ambiortus dementjevi, lived sometime during the Barremian age between 136.4 and 125 million years ago in today's Mongolia. A. dementjevi belongs to the Ornithuromorpha (the group containing modern birds but not enantiornithes), according to all published cladistic analyses. However, the exact position of the species within this group has been controversial. Most analyses have found it to be either an unresolved member of the Ornithurae, or a more primitive member of Ornithuromorpha. One 2006 study, for example, found it to be more primitive than Yanornis but more advanced than Hongshanornis, or even a member of the specific group containing both Yanornis and Yixianornis.The group includes at least Ambiortus and possibly the supposed close relative Apsaravis. The results of a cladistic analysis published in 2011 indicate that Apsaravis and Palintropus are very closely related.


Archaeornithura is an extinct genus of ornithuromorphs from the early Cretaceous period. It is known from two fossil specimens of a single species, Archaeornithura meemannae. The specimens have been dated to the Hauterivian age, 130.7 million years ago, making A. meemannae the oldest known ornithuromorph, the lineage that gave rise to modern birds, and contains all living birds as well as many of their extinct relatives.


Birds, also known as Aves or avian dinosaurs, are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. They rank as the world's most numerically-successful class of tetrapods, with approximately ten thousand living species, more than half of these being passerines, sometimes known as perching birds. Birds have wings which are more or less developed depending on the species; the only known groups without wings are the extinct moa and elephant birds. Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in flightless birds, including ratites, penguins, and diverse endemic island species of birds. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have further evolved for swimming.

The fossil record demonstrates that birds are modern feathered dinosaurs, having evolved from earlier feathered dinosaurs within the theropod group, which are traditionally placed within the saurischian dinosaurs. The closest living relatives of birds are the crocodilians. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period, around 170 million years ago. Many of these early "stem-birds", such as Archaeopteryx, retained primitive characteristics such as teeth and long bony tails. DNA-based evidence finds that birds diversified dramatically around the time of the Cretaceous–Palaeogene extinction event 66 million years ago, which killed off the pterosaurs and all the non-avian dinosaur lineages. But birds, especially those in the southern continents, survived this event and then migrated to other parts of the world while diversifying during periods of global cooling. This makes them the sole surviving dinosaurs according to cladistics.

Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form of culture. Many species annually migrate great distances. Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous (referring to social living arrangement, distinct from genetic monogamy), usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have breeding systems that are polygynous (arrangement of one male with many females) or, rarely, polyandrous (arrangement of one female with many males). Birds produce offspring by laying eggs which are fertilised through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilised, though unfertilised eggs do not produce offspring.

Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds (poultry and game) being important sources of eggs, meat, and feathers. Songbirds, parrots, and other species are popular as pets. Guano (bird excrement) is harvested for use as a fertiliser. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry.


Chaoyangia is an extinct genus of euornithean birds, containing the single species Chaoyangia beishanensis. This species is known from a single fossil specimen consisting of a partial skeleton including vertebra, ribs, hips, and upper legs. The specimen (museum catalog number IVPP V9934) was discovered in the Jiufotang Formation near the city of Chaoyang in Liaoning province, China. This rock formation has been dated to the Aptian age of the Early Cretaceous period, 120 million years ago.


Enantiornithes is a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 80 species of enantiornitheans have been named, but some names represent only single bones, so it is likely that not all are valid. Enantiornitheans became extinct at the Cretaceous–Paleogene boundary, along with hesperornithids and all other non-avian dinosaurs. Enantiornitheans are thought to have left no living descendants.

Hollanda luceria

Hollanda is a genus of small ground birds known from fossils found in the Barun Goyot Formation of Mongolia. Found at Khermeen Tsav, it dates from the late Cretaceous period (Campanian stage), about 75 million years ago. Known only from partial hind limbs, Hollanda has long legs with an unusual configuration of the toes. These indicate that it was a fast-running ground bird, possibly similar to the modern Roadrunner. Its relationships are uncertain. Some studies have found that it was an relatively advanced bird, a member of the Ornithurae, related to birds like Ichthyornis. Other studies have recovered it as a member of the primitive family Songlingornithidae.


Jianchangornis a genus of basal ornithuromorph birds. Fossils were recovered from the Jiufotang Formation at Liaoning, People's Republic of China.


Ornithothoraces is a group of avialans that includes all enantiornithes ("opposite birds") and the euornithes ("true birds"), which includes modern birds and their closest ancestors. The name Ornithothoraces means "bird thoraxes". This refers to the modern, highly advanced anatomy of the thorax that gave the ornithothoracines superior flight capability compared with more primitive avialans. This anatomy includes a large, keeled breastbone, elongated coracoids and a modified glenoid joint in the shoulder, and a semi-rigid rib cage.

The earliest known members of the group are the enantiornitheans Protopteryx fengningensis, Eopengornis martini, and Cruralispennia multidonta, as well as the euornithine Archaeornithura meemannae, all from the Sichakou Member of the Huajiying Formation in China, which has been dated to 130.7 million years old. At least one other enantiornithean, Noguerornis gonzalezi, may be even older, at up to 145.5 million years ago, though its exact age is uncertain.


Ornithurae (meaning "bird tails" in Greek) is a natural group which includes the common ancestor of Ichthyornis, Hesperornis, and all modern birds as well as all other descendants of that common ancestor.


Patagopterygiformes is a group of extinct large Cretaceous terrestrial birds from South America. It contains at most three genera: Patagopteryx, Alamitornis and Kuszholia.


Patagopteryx is an extinct monotypic genus of patagopterygiforms that lived during the Late Cretaceous, around 80 mya, in what is now the Sierra Barrosa in northwestern Patagonia, Argentina. About the size of a chicken, it is the earliest known unequivocal example of secondary flightlessness: its skeleton shows clear indications that the ancestors of Patagopteryx were flying birds.

Located in strata of the Santonian Bajo de la Carpa Formation, the original remains were discovered by Oscar de Ferrariis, Director of the Natural History Museum of the Comahue National University in Neuquén around 1984-5. He passed them onto noted paleontologist José Bonaparte, who described the species Patagopteryx deferrariisi in 1992.


Pengornithidae is a group of early enantiornithines from the early Cretaceous Period of China. Specimens of these animals have been found both in the Huajiying Formation and Jiufotang Formation of Liaoning and Hebei provinces, dating from the Hauterivian age (130.7 million years ago) to the Aptian age (120 million years ago).


Pygostylia is a group of avialans which includes the Confuciusornithidae and all of the more advanced species, the Ornithothoraces.


Schizooura is a genus of basal ornithuromorph bird known from the Early Cretaceous of Jianchang, western Liaoning, China. Its remains were discovered in Jiufotang Formation deposits, dated to 120 million years ago.


Sulcavis is a genus of enantiornithean birds. One species is named, Sulcavis geeorum. The fossil was found in Early Cretaceous (121-125 million years ago) rocks in Liaoning Province, China.

Sulcavis is the first discovery of a bird with ornamented tooth enamel. The enantiornitheans are unique among birds in showing minimal tooth reduction and a diversity of dental patterns. Sulcavis had robust teeth with grooves on the inside surface, which likely strengthened the teeth against harder food items. No previous bird species have preserved ridges, striations, serrated edges, or any other form of dental ornamentation.


For the commune in Botoşani County, Romania, see Vorona, Botoșani.

Vorona ( VOOR-oo-nə; Malagasy for "bird", V. berivotrensis, "from Berivotra") is a monotypic genus of prehistoric birds. It was described from fossils found in a Maevarano Formation quarry near the village of Berivotra, Mahajanga Province, Madagascar. The age is Late Cretaceous, probably Campanian (70.6–83.5 mya). V. berivotrensis is known from scattered remains, possibly from a single individual (UA 8651 and FMNH PA715).

The phylogenic affiliation of Vorona is hard to determine due to the fragmentary nature of the remains, mainly because the fossil shows a mix of primitive avian features as well as some that seem very modern. Vorona might be a primitive ornithuromorph.

Vorona is sometimes confused with the dromaeosaur Rahonavis ostromi, a fossil of which was found in the same location. This confusion has led to the common misconception that Vorona had a deinonychosaur-like sickle claw on each foot.


Wyleyia is a prehistoric bird genus with a single species, Wyleyia valdensis, known from the early Cretaceous period of England. Even this is only known from a single damaged right humerus. It has been named to honor J. F. Wyley, who found the specimen in Weald Clay deposits of Henfield in Sussex (England). The specific name valdensis means "from the Weald".

The bone was found in the Hastings Beds, a series of Valanginian deposits, dated to between 140 and 136 million years ago.Sometimes believed to be from a non-avialan coelurosaur, it is now generally accepted as an early bird, although its exact systematic position is unresolved. It has been proposed to be an enantiornithine or an early neornithine palaeognathe. C.J.O. Harrison and C.A. Walker found it "advisable to consider the new genus incertae sedis until further evidence of affinity is forthcoming."


Zhongjianornis is a genus of beaked, pigeon-sized birds from the early Cretaceous period of China. It is known from one fossil found at Jianchang, Liaoning Province, in rocks of the Jiufotang Formation, representing the type species Zhongjianornis yangi.

The holotype specimen is in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, and the species Z. yangi is named for the IVPP's founder, Yang Zhongjian. This specimen is catalogued under the accession number IVPP V15900. It consists of a complete skeleton, possibly only missing a few tail vertebrae.


Zhyraornis is a genus of prehistoric bird from the late Cretaceous period (middle Turonian, 92 mya). Its fossils have been found in Bissekty Formation deposits near Dzharakuduk in the Kyzyl Kum, Uzbekistan. Two species have been assigned to this genus: Zhyraornis kashkarovi and Zhyraornis logunovi. Both are known only from partial pelvic bones (synsacra).


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