Pedopenna Temporal range: Late Jurassic, | |
---|---|
Reconstruction as an anchiornithid | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | Paraves |
Family: | † Anchiornithidae |
Genus: | † Pedopenna Xu & Zhang, 2005 |
Species: | †P. daohugouensis |
Binomial name | |
†Pedopenna daohugouensis Xu & Zhang, 2005 | |
Pedopenna (meaning "foot feather") is a genus of small, feathered, maniraptoran dinosaur from the Daohugou Beds in China. It is possibly older than Archaeopteryx , though the age of the Daohugou Beds where it was found is debated. A majority of studies suggest that beds probably date from between the late Middle Jurassic (168 million years ago) and early Late Jurassic Period (164-152 million years ago). [1]
The name Pedopenna refers to the long pennaceous feathers on the metatarsus; daohugouensis refers to the locality of Daohugou, where the holotype was found. [2] Pedopenna daohugouensis probably measured 1 meter (3 ft) or less in length, but since this species is only known from the hind legs, the actual length is difficult to estimate. Pedopenna was originally classified as a paravian, the group of maniraptoran dinosaurs that includes both deinonychosaurs and avialans (the lineage including modern birds), but some scientists have classified it as a true avialan more closely related to modern birds than to deinonychosaurs. [3] More recently, it has been recovered as a scansoriopterygid. [4] Lately it was placed to the family Anchiornithidae. [5]
The feet of Pedopenna resembled those of the related troodontids and dromaeosaurids (which together form the group Deinonychosauria), though were overall more primitive. In particular, the second toe of Pedopenna was not as specialized as in deinonychosaurs. While Pedopenna did have an enlarged claw and slightly shortened second toe, it was not as highly developed as the strongly curved, sickle-like claws of its relatives. [2]
Xu Xing and Zhang Fucheng, who interpreted the Daohugou fossil beds where Pedopenna was found as mid to late Jurassic in age, used the presence of such a primitive member of the avian lineage, in combination with many primitive members of closely related lineages there, to support the idea that Avialae originated in Asia. [2]
The bird-like characteristics of Pedopenna are further evidence of the dinosaur-bird evolutionary relationship. Apart from having a very bird-like skeletal structure in its legs, Pedopenna was remarkable due to the presence of long pennaceous feathers on the metatarsus (foot). Some deinonychosaurs are also known to have these 'hind wings', but those of Pedopenna differ from those of deinonychosaurs like Microraptor . Pedopenna hind wings were smaller and more rounded in shape. The longest feathers were slightly shorter than the metatarsus, at about 55 mm (2 in) long. Additionally, the feathers of Pedopenna were symmetrical, unlike the asymmetrical feathers of some deinonychosaurs and birds. Since asymmetrical feathers are typical of animals adapted to flying, it is likely that Pedopenna represents an early stage in the development of these structures. While many of the feather impressions in the fossil are weak, it is clear that each possessed a rachis and barbs, and while the exact number of foot feathers is uncertain, they are more numerous than in the hind-wings of Microraptor. Pedopenna also shows evidence of shorter feathers overlying the long foot feathers, evidence for the presence of coverts as seen in modern birds. Since the feathers show fewer aerodynamic adaptations than the similar hind wings of Microraptor, and appear to be less stiff, suggests that if they did have some kind of aerodynamic function, it was much weaker than in deinonychosaurs and birds.[ citation needed ]
Xu and Zhang, in their 2005 description of Pedopenna, suggested that the feathers could be ornamental, or even vestigial. It is possible that a hind wing was present in the ancestors of deinonychosaurs and birds, and later lost in the bird lineage, with Pedopenna representing an intermediate stage where the hind wings are being reduced from a functional gliding apparatus to a display or insulatory function. [2] This theory may be confirmed by the discovery of Serikornis in 2017, an anchiornithid with soft, symmetrical feathers and filaments on parts of the body that were similar to Pedopenna's.
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.
Dromaeosauridae is a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek δρομαῖος (dromaîos), meaning 'running at full speed', 'swift', and σαῦρος (saûros), meaning 'lizard'. In informal usage, they are often called raptors, a term popularized by the film Jurassic Park; several genera include the term "raptor" directly in their name, and popular culture has come to emphasize their bird-like appearance and speculated bird-like behavior.
Microraptor is a genus of small, four-winged dromaeosaurid dinosaurs. Numerous well-preserved fossil specimens have been recovered from Liaoning, China. They date from the early Cretaceous Jiufotang Formation, 125 to 120 million years ago. Three species have been named, though further study has suggested that all of them represent variation in a single species, which is properly called M. zhaoianus. Cryptovolans, initially described as another four-winged dinosaur, is usually considered to be a synonym of Microraptor.
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Dromaeosauridae, Troodontidae, Oviraptorosauria, and Therizinosauria. Ornitholestes and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria, Maniraptora comprises the more inclusive clade Maniraptoriformes. Maniraptorans first appear in the fossil record during the Jurassic Period, and survive today as living birds.
Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs.
A feathered dinosaur is any species of dinosaur possessing feathers. That includes all species of birds, and in recent decades evidence has accumulated that many non-avian dinosaur species also possessed feathers in some shape or form. The extent to which feathers or feather-like structures were present in dinosaurs as a whole is a subject of ongoing debate and research.
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.
Scansoriopteryx is a genus of maniraptoran dinosaur. Described from only a single juvenile fossil specimen found in Liaoning, China, Scansoriopteryx is a sparrow-sized animal that shows adaptations in the foot indicating an arboreal (tree-dwelling) lifestyle. It possessed an unusual, elongated third finger which may have supported a membranous wing, much like the related Yi qi. The type specimen of Scansoriopteryx also contains the fossilized impression of feathers.
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.
Jeholornis is a genus of avialan dinosaurs 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 and additional specimens have been found in the older Yixian Formation.
The scientific question of within which larger group of animals birds evolved has traditionally been called the "origin of birds". The present scientific consensus is that birds are a group of maniraptoran theropod dinosaurs that originated during the Mesozoic era.
Avialae 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 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.
Epidexipteryx is a genus of small maniraptoran 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.
Eosinopteryx is an extinct genus of theropod dinosaurs known to the Late Jurassic epoch of China. It contains a single species, Eosinopteryx brevipenna.
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 small paravian dinosaurs. Anchiornithids have been classified at varying positions in the paravian 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.