Feathered dinosaur

A feathered dinosaur is a dinosaur with feathers. It is now thought that all coelurosaurs, and perhaps all theropods, had feathers.

The possibility that dinosaurs are closely related to birds raised the possibility of feathers. Fossils of Archaeopteryx include well-preserved feathers, but it was not until the early 1990s that clearly non-bird dinosaur fossils were discovered with preserved feathers. About 40 genera of theropods are now known to be feathered.

Most of these fossils come from the Yixian formation in China. The fossil feathers of one specimen, Shuvuuia deserti, have been tested positive for beta-keratin in immunological tests. This is the main protein in bird feathers.

 Fossil evidence 

After a century without clear evidence, well-preserved fossils of feathered dinosaurs were discovered during the 1990s, and more continue to be found. The fossils were preserved in a Lagerstätte — a sedimentary deposit exhibiting remarkable richness and completeness in its fossils — in  Liaoning, China.

The area had repeatedly been smothered in volcanic ash by eruptions in Inner Mongolia 124 million years ago, during the Lower Cretaceous. The fine-grained ash preserved the living organisms that it buried in fine detail. The area was teeming with life, with millions of leaves, angiosperms (the oldest known), insects, fish, frogs, salamanders, mammals, turtles, lizards and crocodilians discovered to date.

The most important discoveries at Liaoning have been a host of feathered dinosaur fossils, with a steady stream of new finds filling in the picture of the dinosaur-bird connection and adding more to theories of the evolutionary development of feathers and flight. Quill knobs were found an ulna of Velociraptor mongoliensis. These are associated with large, well-developed secondary feathers.
Behavioural evidence, in the form of an oviraptorosaur on its nest, showed another link with birds. Its forearms were folded, like those of a bird. Although no feathers were preserved, it is likely that these would have been present to keep eggs and juveniles warm.Hopp, Thomas J. & Orsen, Mark J. 2004. In Philip J. Currie, Eva B. Koppelhus and Martin A. Shugar (eds) Feathered Dragons: studies on the transition from dinosaurs to birds. Chapter 11: Dinosaur brooding behavior and the origin of flight feathers. Indiana University Press. Bloomington IN. USA.

 Evidence in amber 
The feathered tail of a non-avialan (non-bird) theropod has been found preserved in mid-Cretaceous (∼99 mya) amber from Kachin State, Myanmar (Burma).Lida Xing et al 2016. A feathered dinosaur tail with primitive plumage trapped in mid-Cretaceous amber. Current Biology.  The BBC describe it as "perfectly preserved".Rincon, Paul 2016. 'Beautiful' dinosaur tail found preserved in amber. BBC News Science & Environment.  Lida Xing found it at an amber market in Myitkina, Myanmar. The amber was already polished for jewellery: the seller thought it was plant material. However, it was the tail of a feathered dinosaur about the size of a sparrow. The feathers were not flight feathers. Dr Paul Barrett, from London's Natural History Museum, called the specimen a "beautiful fossil", describing it as a "really rare occurrence of vertebrate material in amber".

 Cretaceous period 
In 2011, samples of amber were discovered to contain preserved feathers from the Cretaceous period, with evidence that they were from both dinosaurs and birds. Initial analysis suggests that some of the feathers were used for insulation, and not flight.CBC News: Dinosaur feathers found in Alberta amberBBC News: Dinosaur feather evolution trapped in Canadian amber

 Current knowledge 
 List of dinosaurs with evidence of feathers 

Many non-avialan dinosaurs are now known to have been feathered. Direct evidence of feathers exists for the following genera, listed in the order of when the evidence was first published.

The evidence consists of feather impressions, or convincing skeletal or chemical evidence. Skeletal evidence would be the presence of quill knobs (the anchor points for wing feathers on the forelimb) or a pygostyle (the fused vertebrae at the tail tip which often supports large feathers).

For comparison: Archaeopteryx (1861; avialan)von Meyer H. 1861. Archaeopteryx litographica (Vogel-Feder) und Pterodactylus von Solenhofen. Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefakten-Kunde. 1861: 678–679, plate V [Article in German] Fulltext at Google Books. definitely had working flight feathers with off-centre rachis (stem). Otherwise, apart from the front limbs, it was a typical small carnivorous dinosaur.

 Avimimus portentosus (inferred 1987: quill knobs)Kurzanov S.M. 1987. Avimimidae and the problem of the origin of birds. Transactions of the Joint Soviet-Mongolian Paleontological Expedition, 31: 5-92. [in Russian]Chiappe L.M. and Witmer L.M. 2002. Mesozoic Birds: above the heads of dinosaurs. Berkeley: University of California Press. 
 Sinosauropteryx prima (1996)
 Protarchaeopteryx robusta (1997)Ji, Q. and Ji, S. 1997. A Chinese archaeopterygian, Protarchaeopteryx gen. nov." Geological Science and Technology (Di Zhi Ke Ji), 238: 38-41. Translated By Will Downs Bilby Research Center Northern Arizona University January 2001
 GMV 2124 (1997).
 Caudipteryx zoui (1998)

 Shuvuuia deserti (1999)
 Sinornithosaurus millenii (1999)
 Beipiaosaurus inexpectus (1999)
 Caudipteryx dongi (2000)
 Caudipteryx sp. (2000)
 Microraptor zhaoianus (2000)
 Nomingia gobiensis (inferred 2000: pygostyle)
 Psittacosaurus sp.? (2002)
 Scansoriopteryx heilmanni (2002)Czerkas S.A. and Yuan C. 2002. An arboreal maniraptoran from northeast China. In Czerkas S.J. (ed) Feathered dinosaurs and the origin of flight, 63-95. The Dinosaur Museum Journal 1. The Dinosaur Museum, Blanding, U.S.A. PDF abridged version
 Yixianosaurus longimanus (2003)
 Dilong paradoxus (2004)

 Jinfengopteryx elegans (2005)
 Juravenator starki (2006)
 Sinocalliopteryx gigas (2007)
 Velociraptor mongoliensis (inferred 2007: quill knobs)
 Epidexipteryx hui (2008) 
 Similicaudipteryx yixianensis (inferred 2008: pygostyle; confirmed 2010)
 Zhongornis haoae (2008)Gao, Cunling et al (2008) A new basal lineage Of early Cretaceous birds from China and its implications on the evolution of the avian tail. Palaeontology  51, Part 4, pp. 775-791. 

 Tianyulong confuciusi? (2009)
 Concavenator corcovatus? (inferred 2010: quill knobs?)

 Yutyrannus huali (2012)
 Microraptor hanqingi (2012)
 Ornithomimus edmontonicus (2012)
 Ningyuansaurus wangi (2012)
 Eosinopteryxbrevipenna (2013)
 Citipati osmolskae (inferred 2013: pygostyle)
 Conchoraptor gracilis (inferred 2013: pygostyle)
 Jianchangosaurus yixianensis (2013)
 Aurornis xui (2013; possibly avialan)
 Changyuraptor yangi (2014)
 Kulindadromeus zabaikalicus? (2014)
 Citipati osmolskae (inferred 2014: pygostyle)
 Conchoraptor gracilis (inferred 2014: pygostyle)
 Deinocheirus mirificus (inferred 2014: pygostyle)
 Yi qi (2015)Xu, X. et al 2015. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings. Nature. 

 Note, filamentous structures in some ornithischian dinosaurs (Psittacosaurus, Tianyulong) and pterosaurs may or may not be homologous with the feathers and protofeathers of theropods.Czerkas S.A., and Ji Q. 2002. A new rhamphorhynchoid with a headcrest and complex integumentary structures. Pp. 15-41 in: Czerkas, S.J. (Ed.). Feathered dinosaurs and the origin of flight. Blanding, Utah: The Dinosaur Museum. .

 Related pages 
Avialae
Dinobird
Coelurosaur

 References 

Category:Coelurosaurs