| Eosinopteryx Temporal range: Late Jurassic, | |
|---|---|
 | |
| Life restoration | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | † Anchiornithidae |
| Genus: | † Eosinopteryx Godefroit et al., 2013 |
| Type species | |
| †Eosinopteryx brevipenna Godefroit et al., 2013 | |
Eosinopteryx is an extinct genus of theropod dinosaurs known to the Late Jurassic epoch of China. It contains a single species, Eosinopteryx brevipenna. [1]
E. brevipenna is known from a single fossil specimen recovered from the Tiaojishan Formation of western Liaoning Province, China, which has been dated to the late Jurassic period (Oxfordian age), about 160 million years ago. [2] [3] The name Eosinopteryx is derived from the Greek eos ("daybreak" or "dawn"), the Latin Sinae ("Chinese"), and the Greek pteryx ("feather"). The specific name brevipenna (from the Latin brevis, "short", and penna, "feather") refers to the reduced plumage preserved in the type specimen, YFGP-T5197. [1]
Eosinopteryx brevipenna is known from a single fossil specimen representing the nearly complete skeleton of a subadult or adult individual. The specimen is very small for a non-avialan dinosaur, measuring about 30 centimetres (12 in) long. Unlike most troodontids, the snout was very short, shorter than the diameter of the eye socket. The wings were about the same size as those of the related Anchiornis huxleyi , with the primary wing feathers being longer than the humerus (upper arm bone). An unusual arrangement of the wing bones would have prevented any flapping motion.
The tail was very short compared to most troodontids and dromaeosaurids and also unlike members of those groups, the feet and toes were very slender, lacking highly curved claws for predation or climbing. Unusually, the tail of the only known fossil does not show signs of the presence of complex vaned feathers (rectrices), and the lower tarsals and feet appear to have been featherless, unlike many related species with "hind wings" on the lower legs and feet. [1]
A researcher from the University of Southampton said in 2013 the discovery of Eosinopteryx suggests "that the origin of flight was much more complex than previously thought". [4]
A 2017 study describing new specimens of Anchiornis found Eosinopteryx only distinguishable from Anchiornis in the length of the tail, [5] but the tail of Eosinopteryx is incomplete, [6] rendering this distinction invalid. This led some researchers to consider Eosinopteryx a junior synonym of Anchiornis. [7]
Though initially classified as a troodontid, [1] a more comprehensive analyses of its relationships have found it to be either a primitive paravian or an avialan. [8] In 2017 re-evaluation of the Harlem Archaeopteryx specimen, Eosinopteryx is found to be an anchiornithid. [9]
Archaeopteryx, sometimes referred to by its German name, "Urvogel", is a genus of avian dinosaurs. The name derives from the ancient Greek ἀρχαῖος (archaīos), meaning "ancient", and πτέρυξ (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. Older potential avialans have since been identified, including Anchiornis, Xiaotingia, and Aurornis.
Troodontidae is a clade of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discoveries of complete and articulated specimens, have helped to increase understanding about this group. Anatomical studies, particularly studies of the most primitive troodontids, like Sinovenator, demonstrate striking anatomical similarities with Archaeopteryx and primitive dromaeosaurids, and demonstrate that they are relatives comprising a clade called Paraves.
Deinonychosauria is a clade of paravian dinosaurs which lived from the Late Jurassic to the Late Cretaceous periods. Fossils have been found across the globe in North America, Europe, Africa, Asia, South America, and Antarctica, with fossilized teeth giving credence to the possibility that they inhabited Australia as well. This group of dinosaurs are known for their sickle-shaped toe claws and features in the shoulder bones.
Jinfengopteryx is a genus of maniraptoran dinosaur. It was found in the Qiaotou Member of the Huajiying Formation of Hebei Province, China, and is therefore of uncertain age. The Qiaotou Member may correlate with the more well-known Early Cretaceous Yixian Formation, and so probably dates to around 122 Ma ago.
Yixianosaurus is a maniraptoran theropod dinosaur genus from the Early Cretaceous of China.
Scansoriopterygidae 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 of Liaoning and Hebei, China.
Yandangornis is a genus of theropods from the Late Cretaceous Tangshang Formation of China. 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.
Maniraptoriformes is a clade of dinosaurs with pennaceous feathers and wings that contains ornithomimosaurs and maniraptorans. This group was named by Thomas Holtz, who defined it as "the most recent common ancestor of Ornithomimus and birds, and all descendants of that common ancestor."
Avialae 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.
Paraves are a widespread group of theropod dinosaurs that originated in the Middle Jurassic period. In addition to the extinct dromaeosaurids, troodontids, anchiornithids, and possibly the scansoriopterygids, the group also contains the avialans, which include diverse extinct taxa as well as the over 10,000 species of living birds. Basal members of Paraves are well known for the possession of an enlarged claw on the second digit of the foot, which was held off the ground when walking in some species. A number of differing scientific interpretations of the relationships between paravian taxa exist. New fossil discoveries and analyses make the classification of Paraves an active subject of research.
Epidexipteryx is a genus of small paravian dinosaurs, 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.
Anchiornis is a genus of small, four-winged paravian dinosaurs, with only one known species, the type species Anchiornis huxleyi, named for its similarity to modern birds. The Latin name Anchiornis derives from a Greek word meaning "near bird", and huxleyi refers to Thomas Henry Huxley, a contemporary of Charles Darwin.
Xiaotingia is a genus of anchiornithid theropod dinosaur from Middle Jurassic or early Late Jurassic deposits of western Liaoning, China, containing a single species, Xiaotingia zhengi.
Aurornis is an extinct genus of anchiornithid theropod dinosaurs from the Jurassic period of China. The genus Aurornis contains a single known species, Aurornis xui. Aurornis xui may be the most basal ("primitive") avialan dinosaur known to date, and it is one of the earliest avialans found to date. The fossil evidence for the animal pre-dates that of Archaeopteryx lithographica, often considered the earliest bird species, by about 10 million years.
Jianianhualong is a genus of troodontid theropod dinosaur from the Early Cretaceous of China. It contains a single species, Jianianhualong tengi, named in 2017 by Xu Xing and colleagues based on an articulated skeleton preserving feathers. The feathers at the middle of the tail of Jianianhualong are asymmetric, being the first record of asymmetrical feathers among the troodontids. Despite aerodynamic differences from the flight feathers of modern birds, the feathers in the tail vane of Jianianhualong could have functioned in drag reduction whilst the animal was moving. The discovery of Jianianhualong supports the notion that asymmetrical feathers appeared early in the evolutionary history of the Paraves.
Liaoningvenator is a genus of troodontid theropod dinosaur from the Early Cretaceous of China. It contains a single species, L. curriei, named after paleontologist Phillip J. Currie in 2017 by Shen Cai-Zhi and colleagues from an articulated, nearly complete skeleton, one of the most complete troodontid specimens known. Shen and colleagues found indicative traits that placed Liaoningvenator within the Troodontidae. These traits included its numerous, small, and closely packed teeth, as well as the vertebrae towards the end of its tail having shallow grooves in place of neural spines on their top surfaces.
Serikornis is a genus of small, feathered anchiornithid dinosaur from the Upper Jurassic Tiaojishan Formation of Liaoning, China. It is represented by the type species Serikornis sungei.
Anchiornithidae is a family of eumaniraptorans which could be the basalmost family of birds 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.
Caihong is a genus of small paravian theropod dinosaur from China that lived during the Late Jurassic period.
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