Epidexipteryx ("display feather") is a genus of small avialan dinosaur, known from one fossil specimen in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. Epidexipteryx represents the earliest known example of ornamental feathers in the fossil record. The type specimen is catalog number IVPP V 15471. It has been reported to be a maniraptoran dinosaur from the Middle Jurassic or Upper Jurassic age Daohugou Beds of Inner Mongolia, China (about 152 to 168 mya).

 The specific name, Epidexipteryx hui ("Hu's display feather"), and its Chinese name Hushi Yaolong ("Hu Yaoming's dragon") were coined in memory of paleomammologist Hu Yaoming.

 It is known from a well preserved partial skeleton that includes four long feathers on the tail, composed of a central rachis and vanes. However, unlike in modern-style rectrices (tail feathers), the vanes were not branched into individual filaments but made up of a single ribbon-like sheet. Epidexipteryx also preserved a covering of simpler body feathers, composed of parallel barbs as in more primitive feathered dinosaurs. However, the body feathers of Epidexipteryx are unique in that some appear to arise from a "membranous structure" at the base of each feather. It has been suggested that this may represent a stage in the evolution of the feather.

 In all, the skeleton of Epidexipteryx hui measures 25 centimeters (10 inches) in length (44.5 cm or 17.5 in including the incomplete tail feathers), and the authors estimated a weight of 164 grams, smaller than most other basal avialans.

 The skull of Epidexipteryx is also unique in a number of features, and bears an overall similarity to the skull of Sapeornis, oviraptorosaurs and, to a lesser extent, therizinosauroids. It had teeth only in the front of the jaws, with unusually long front teeth angled forward, a feature only seen in Masiakasaurus among other theropods. The rest of the skeleton bore an overall similarity to the closely related Scansoriopteryx, including a hip configuration unusual among other dinosaurs: the pubis was shorter than the ischium, and the ischium itself was expanded towards the tip. However, the tail of Epidexipteryx differed significantly from Scansoriopteryx. In Scansoriopteryx, the tail was long, about 300% of total trunk length, while the short tail of Epidexipteryx was only 70% of its trunk length. The tail of Epidexipteryx also bore unusual vertebrae towards the tip which resembled the feather-anchoring pygostyle of modern birds and some oviraptorosaurs.

 Despite its close relationship to avialan birds, Epidexipteryx appears to have lacked remiges (wing feathers), and it likely could not fly. Zhang et al. suggest that unless Epidexipteryx evolved from flying ancestors and subsequently lost its wings, this may indicate that advanced display feathers on the tail may have predated flying or gliding flight.

 У птиц в очередной раз сменился «самый старший предок». Эпидексиптерикс Ху, или Epidexipteryx hui по латыни, может войти в учебники биологии наравне с археоптериксом, которого новый юрский вид старше. По мнению китайских учёных, нашедших окаменелость во Внутренней Монголии, первенство эпидексиптерикса доказывает его хвост.

 Происхождение птиц – если и не уникальный, то, наверное, самый спорный момент в эволюции. Хотя гипотетическое описание переходной формы от динозавров к птицам создано более века назад, ископаемые виды, занимающие это почётное место, регулярно меняются – конечно, не по своей воле, а благодаря ученым, требующим торжества истины, а может быть, просто желающим увековечить свое имя в названии вида.

 Очередная смена «царя горы», может быть, и осталась бы незамеченной, но только не в русскоговорящей научной среде. И все благодаря знаменитому китайскому специалисту по животным мезозойской эры Яомину Ху, скончавшемуся в апреле этого года. Коллеги покойного палеонтолога по Институту палеонтологии позвоночных и палеоантропологии Китайской академии наук увековечили в видовом имени нового ископаемого фамилию Ху.

 По мнению китайских палеонтологов, Epidexipteryx hui, окаменелости которого датируются промежутком с 152-го до 168-го миллионов лет назад, должен расположиться у основания всего клада Avialae. В эту группу входят не только птицы, но и их ближайшие родственники среди динозавров. И хотя для окончательных выводов о роли эпидексиптерикса (от греческого «показывающий перья») в эволюции необходимо провести дополнительные сравнения и, что немаловажно, заручиться поддержкой коллег, у «пернатого динозаврика» есть все шансы стать предком самого археоптерикса.

 По мнению Фучэна Чжана и его коллег, эпидексиптерикс Ху должен располагаться у основания клада Avialae, включающего всех птиц и их динозавровых родственников. Эпидексиптериксов и эпидендрозавров учёные выделили в клад Scansoriopterigidae, однако несколько признаков заставляют их всё же отдать «первенство» именно новооткрытому виду.

 Находка была сделана во Внутренней Монголии на территории Китая и относится к средней или верхней эпохе юрского периода, что совпадает с современными представлениями о возникновении и эволюции пернатых. Облик эпидексиптерикса тоже неплохо вписывается в эти самые современные представления. Небольшой размер, масса около 160 грамм, выступающая нижняя челюсть с уплощенными, хотя и увеличенными зубами, но главное, как водится, – хвост.

 Конечно, не такой, как у птиц, но уже и не такой, как у рептилий. Сросшиеся хвостовые позвонки, на конце увенчанные четырьмя торчащими перьеподобными структурами.

 Именно такой хвост позволил Фучэну Чжану и его коллегам говорить о преимуществах эпидексиптерикса перед эпидендрозаврами, ранее располагавшимися в основании ветви Avialae. Во-первых, у эпидексиптерикса хвост короче – всего лишь 70% от длины тела, а не все 300%, как у эпидендрозавров. Во-вторых, у E.hui меньше позвонков – 16 против 40 у большинства эпидендрозавров, и они более плоские.

 Крыльев как таковых у эпидексиптерикса не было, хотя скелет передних конечностей уже близок к таковому у птиц. Отсутствие контурных перьев делало полет физически невозможным.

 Как отметили учёные, эта группа активно экспериментировала с оперением и строением скелета, а именно в этом заключаются принципиальные отличия птиц, сделавшие возможным полёт. Остальные особенности, среди которых интенсивный обмен веществ и идеальная нервная система, совершенствовались уже «в полете» за счет внутренней конкуренции.

 Scansoriopterygidae (meaning "climbing wings") is a family of maniraptoran dinosaurs, known from three well-preserved fossils unearthed in the Daohugou fossil beds (possibly dating to the mid-late Jurassic Period) of Liaoning, China.

 Scansoriopteryx (and its likely synonym Epidendrosaurus) 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 in 2008 that an adult specimen was known. The type specimen of Scansoriopteryx (type genus of the Scansoriopterygidae) and its arboreal adaptations were first presented in 2000 during the Florida Symposium on Dinosaur/Bird Evolution, at the Graves Museum of Archaeology & Natural History, though the specimen would not be formally described and named until 2002.

 Scansoriopterygids are among the smallest dinosaurs known. The juvenile specimens of Scansoriopteryx are the size of House Sparrows, about 16 centimeters long, while the adult type specimen of Epidexipteryx is about the size of a Pigeon, about 25 centimeters long (not including the tail feathers).

 Scansoriopterygids can be characterized by their extremely elongated third fingers, which are longer than the first and second digits of the hand (in all other known theropods, the second finger is the longest). Other features shared within the group include short and high skulls with down turned lower jaws and large front teeth, and long arms. Tail length, however, varied significantly among scansoriopterygids. Epidexipteryx had a short tail (70% the length of the torso), anchoring long tail feathers, while Scansoriopteryx had a very long tail (over three times as long as the torso) with a short spray of feathers at the tip. All three described scansoripterygid specimens preserve the fossilized traces of feathers covering their bodies.

 Scansoriopterygidae was created as a family-level taxon by Stephen Czerkas and Yuan Chongxi in 2002. Some scientists, such as Paul Sereno, initially considered the concept redundant because the group was originally monotypic, containing only the single genus and species Scansoriopteryx heilmanni. Additionally, the group lacked a phylogenetic definition. However, in 2008 Zhang et al. reported another scansoriopterygid, Epidexipteryx, and defined Scansoriopterygidae as a clade comprising most recent common ancestor of Epidexipteryx and Epidendrosaurus (=Scansoriopteryx") plus all its descendants.

 The exact taxonomic placement of this group was initially uncertain and controversial. When describing the first validly published specimen in 2002 (Scansoriopteryx heilmanni), Czerkas and Yuan proposed that various primitive features of the skeleton (including a primitive, "saurischian-style" pubis and primitive hip joint) showed that scansoriopteryds, along with other maniraptorans and birds, split from other theropods very early in dinosaur evolution. However, this interpretation has not been followed by most other researchers. In a 2007 cladistic analysis of relationships among coelurosaurs, Phil Senter found Scansoriopteryx to be the closest dinosaurian relative of avian birds, and a member of the clade Avialae. This view was supported by a second phylogenetic analysis performed by Zhang et al. in 2008. These authors included the additional taxon Epidexipteryx, and found that it formed a clade with Scansoriopteryx at the base of Avialae.

 Avialae ("bird wings") is a clade of dinosaurs containing their only living representatives, birds (Aves), and the most immediate extinct relatives of birds.

 Systematic studies of the Avialae have produced different results depending on the specimens included and the definitions used. Including or excluding Archaeopteryx from the group Aves has a large effect on the subgroups of Avialae. Archaeopteryx, from the late Jurassic Period, may be the earliest known theropod dinosaur which may have had the capability of powered flight. If Archaeopteryx is defined as an avian, then there are few non-avian avialans.

 Avialae is traditionally defined as an apomorphy-based clade (that is, one based on physical characteristics). Jacques Gauthier named Avialae in 1986, and first defined it in 2001 as all dinosaurs that possessed feathered wings used in flapping flight, and the birds that descended from them.

 Gauthier identified four conflicting ways of defining the term "Aves", which is a problem because the same biological name is being used four different ways. Gauthier proposed a solution, number 4 below, which is to reserve the term Aves only for the crown group, the last common ancestor of all living birds and all of its descendants. He assigned other names to the other groups.

1. Aves can mean those advanced archosaurs with feathers (alternately Avifilopluma)
2. Aves can mean those that fly (alternately Avialae)
3. Aves can mean all reptiles closer to birds than to crocodiles (alternately Avemetatarsalia [=Panaves])
4. Aves can mean the last common ancestor of all the currently living birds and all of its descendants (a "crown group"). (alternately Neornithes)

 Under the fourth definition Archaeopteryx is an avialan, and not a member of Aves.

 Several authors have use a similar, but branch-based, definition; "all theropods closer to birds than to Deinonychus."

 Репродукции (1, 2, 3, 4, 5, 6, 7, 8):

 Размеры тела в сравнении с человеком и анхиорнисом (закрашен зелёным цветом):

 Ископаемые останки (1, 2, 3):

Tags: Вымершие рептилии, Юра, авеметатарзалии, авиалы, архозавроморфы, архозавры, диапсиды, динозавроморфы, динозавры, манирапторы, скансориоптеригиды, тероподы, целурозавры, ящеротазовые

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