Avialans
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Avialans
Avialae ("bird wings") is a clade containing the only living dinosaurs, the birds. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to deinonychosaurs, though alternative definitions are occasionally used (see below). ''Archaeopteryx lithographica'', from the late Jurassic Period Solnhofen Formation of Germany, is possibly the earliest known avialan which may have had the capability of powered flight, though it might have been a deinonychosaur instead. Several older (but non flight-capable) avialans are known from the late Jurassic Tiaojishan Formation of China, dated to about 160 million years ago. Definition Most researchers define Avialae as branch-based clade, though definitions vary. Many authors have used a definition similar to "all theropods closer to birds than to ''Deinonychus''."Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.) (2004). ''The Dinosauria'', Second Edition. University of California Press., 861 pp. ...
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Jeholornis Prima
''Jeholornis'' (meaning "Jehol bird") is a genus of avialans that lived between approximately 122 and 120 million years ago during the early Cretaceous Period in China. Fossil ''Jeholornis'' were first discovered in the Jiufotang Formation in Hebei Province, China (in what was previously Rehe Province, also known as Jehol—hence the name) and additional specimens have been found in the older Yixian Formation. ''Jeholornis'' had long tails and few small teeth, and were approximately the size of turkeys,Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages'Supplementary Information/ref> making them among the largest avialans known until the Late Cretaceous. Their diet included seeds of cycads, ''Ginkgo'' or similar plants. Description ''Jeholornis'' were relatively large, basal avialans, with a maximum adult length of up to 75 cm (2.5 ft) and an estimated weight of 2.27-9.1 kg (5-20 lbs). Another ...
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Anchiornithidae
Anchiornithidae ("near birds") is a family of eumaniraptorans which could be the basalmost family of birds (in the general sense) in the clade Avialae. Anchiornithids have been classified at varying positions in the maniraptoran tree, with some scientists classifying them as a distinct family, a basal subfamily of Troodontidae, members of Archaeopterygidae, or an assemblage of dinosaurs that are an evolutionary grade within Avialae or Paraves. Description Anchiornithids share many general features with other Paraves and early avialans. They were small and lightly-built feathered carnivores, similar in biology to ''Archaeopteryx'', early dromaeosaurids like ''Microraptor'', and particularly troodontids. They are almost exclusively known from Late Jurassic Chinese deposits, although ''Ostromia'' was discovered in Germany and ''Yixianosaurus'' (a putative member of the group only known from forelimbs) is believed to hail from the early Cretaceous. Most had long legs, arms, and ha ...
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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 lightweight skeleton. Birds live worldwide and range in size from the bee hummingbird to the ostrich. There are about ten thousand living species, more than half of which are passerine, or "perching" birds. Birds have whose development varies according to species; the only known groups without wings are the extinct moa and elephant birds. Wings, which are modified forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in some birds, including ratites, penguins, and diverse endemic island species. 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. B ...
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Yandangornis
''Yandangornis'' is a genus of theropods (possibly avialans) from the Late Cretaceous. It lived 81.5 million years ago in what is now China. The type species, ''Y. longicaudus'', was formally described by Cai and Zhou in 1999. The holotype specimen is a mostly complete skeleton in the collection of the Zhejiang Museum of Natural History, with accession number M1326. The fossil was discovered in 1986, near Linhai City in Zhejiang Province, China. It includes most of one complete skeleton. The genus was named after the Yandang mountains. Description The specimen is small, roughly the size of ''Archaeopteryx'', with a total length around , of which 30.5 centimeters (1 foot) is tail. It is preserved in a seated position and visible from the ventral aspect. After ''Archaeopteryx'', ''Yandangornis'' was the second genus of primitive bird found preserving a long, bony tail, and this trait was responsible for the specific name ''longicaudus,'' which is Latin for "long tail". The skull ...
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Archaeopteryx Lithographica
''Archaeopteryx'' (; ), sometimes referred to by its German name, "" ( ''Primeval Bird''), is a genus of bird-like dinosaurs. The name derives from the ancient Greek (''archaīos''), meaning "ancient", and (''ptéryx''), meaning "feather" or "wing". Between the late 19th century and the early 21st century, ''Archaeopteryx'' was generally accepted by palaeontologists and popular reference books as the oldest known bird (member of the group Avialae). Older potential avialans have since been identified, including ''Anchiornis'', ''Xiaotingia'', and ''Aurornis''. ''Archaeopteryx'' lived in the Late Jurassic around 150 million years ago, in what is now southern Germany, during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now. Similar in size to a Eurasian magpie, with the largest individuals possibly attaining the size of a raven, the largest species of ''Archaeopteryx'' could grow to about in leng ...
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Theropod
Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores and omnivores. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago ( Ma) and included all the large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by about 10,500 living species. Biology Diet and teeth Theropods exhibit a wide range of diets, from insectivores to herbivores and carnivores. Strict carnivory has always been considered the ancestral diet for theropods as a group, and a wider variety of diets was historically considered a characteri ...
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Balaur Bondoc
''Balaur bondoc'' is a species of theropod dinosaur from the late Cretaceous period, in what is now Romania. It is the type species of the monotypic genus ''Balaur'', after the ''balaur'' (), a dragon of Romanian folklore. The specific name ''bondoc'' () means "stocky", so ''Balaur bondoc'' means "stocky dragon" in Romanian. This name refers to the greater musculature that ''Balaur'' had compared to its relatives. The genus, which was first described by scientists in August 2010, is known from two partial skeletons (including the type specimen). Fossils of ''Balaur'' were found in the Densuş-Ciula and Sebeș Formations of Cretaceous Romania which correspond to Hațeg island, a subtropical islandBenton, M.J., Csiki, Z., Grigorescu, D., Redelstorff, R., Sander, P.M., Stein, K., and Weishampel, D.B. (2010).Dinosaurs and the island rule: The dwarfed dinosaurs from Hațeg Island." ''Palaeogeography, Palaeoclimatology, Palaeoecology'', 293(3-4): 438–454. in the European archipelag ...
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Jurassic Period
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined. By the beginning of the Jurassic, t ...
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Euavialae
Euavialae (meaning "true winged birds") is a group of theropods which includes all avialan species more closely related to modern birds than to the basal, long-tailed avialans ''Archaeopteryx ''Archaeopteryx'' (; ), sometimes referred to by its German name, "" ( ''Primeval Bird''), is a genus of bird-like dinosaurs. The name derives from the ancient Greek (''archaīos''), meaning "ancient", and (''ptéryx''), meaning "feather" ...'' and '' Shenzhouraptor''.Ji, Q.; Ji, S.; Zhang, H.; You, H.; Zhang, J.; Wang, L.; Yuan, C. & Ji, X. (2002): A new avialan bird - ''Jixiangornis orientalis'' gen. et sp. nov. - from the Lower Cretaceous of Western Liaoning, NE China. ''Journal of Nanjing University (Natural Sciences)'' 38(6): 723-736 n Chinese with English abstract Cladogram following the results of a phylogenetic study by Lefèvre ''et al.'', 2014: References Avialans Extant Early Cretaceous first appearances {{Theropod-stub ...
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Scansoriopterygidae
Scansoriopterygidae (meaning "climbing wings") is an extinct family of climbing and gliding maniraptoran dinosaurs. Scansoriopterygids are known from five well-preserved fossils, representing four species, unearthed in the Tiaojishan Formation fossil beds (dating to the mid-late Jurassic Period) of Liaoning and Hebei, China. '' Scansoriopteryx heilmanni'' (and its likely synonym ''Epidendrosaurus ninchengensis'') was the first non-avian dinosaur found that had clear adaptations to an arboreal or semi-arboreal lifestyle–it is likely that they spent much of their time in trees. Both specimens showed features indicating they were juveniles, which made it difficult to determine their exact relationship to other non-avian dinosaurs and birds. It was not until the description of '' Epidexipteryx hui'' in 2008 that an adult specimen was known. In 2015, the discovery of another, larger adult specimen belonging to the species '' Yi qi'' showed that scansoriopterygids were not onl ...
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Jeholornithidae
Jeholornithidae is a family of avialan theropods whose taxonomy is controversial, whose remains are found in fossil deposits of what is now China. The controversy stems from whether most of the taxa in the group are just specimens of ''Jeholornis'', as well as if the group is monophyletic at all. In the description of '' Kompsornis'' the authors Wang ''et al''. (2020) found moderate support in the monophyly of the group, placing them as basal avialans sister to Pygostylia. No 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 ... definitions for these groups were provided by Zhou and Zhang, but a topological definition was provided in 2020 by Wang and colleagues where Jeholornithiformes was defined as "the most inclusive clade containing ''Je. prima'' but excluding the exta ...
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Rahonavis
''Rahonavis'' is a genus of bird-like theropods from the Late Cretaceous (Maastrichtian, about 70 mya) of what is now northwestern Madagascar. It is known from a partial skeleton ( UA 8656) found by Catherine Forster and colleagues in Maevarano Formation rocks at a quarry near Berivotra, Mahajanga Province.Tudge, Colin (2009) ''The Bird:A Natural History of Who Birds Are, Where They Came From, and How They Live'/ref> ''Rahonavis'' was a small predator, at about long and 0.45-2.27 kg (1-5 lbs),Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages'Supplementary Information/ref> with the typical ''Velociraptor''-like raised sickle claw on the second toe. It was originally the first African coelurosaur until the Nqwebasaurus was discovered in 2000. The name ''Rahonavis'' means, approximately, "cloud menace bird", from Malagasy ' (RA-hoo-na, "cloud" or "menace") + Latin ' "bird". The specific name, ''R. ostromi'', was co ...
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