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.

### 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). The BBC describe it as "perfectly preserved". 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.

### 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) definitely had working flight feathers with off-centre rachis (stem). Otherwise, apart from the front limbs, it was a typical small carnivorous dinosaur.

1. _Avimimus portentosus_ (inferred 1987: quill knobs)
1. _Sinosauropteryx prima_ (1996)
1. _Protarchaeopteryx robusta_ (1997)
1. GMV 2124 (1997).
1. _Caudipteryx zoui_ (1998)

1. _Shuvuuia deserti_ (1999)
1. _Sinornithosaurus millenii_ (1999)
1. _Beipiaosaurus inexpectus_ (1999)
1. _Caudipteryx dongi_ (2000)
1. _Caudipteryx_ sp. (2000)
1. _Microraptor zhaoianus_ (2000)
1. _Nomingia gobiensis_ (inferred 2000: pygostyle)
1. _Psittacosaurus_ sp.? (2002)
1. _Scansoriopteryx heilmanni_ (2002)
1. _Yixianosaurus longimanus_ (2003)
1. _Dilong paradoxus_ (2004)

1. _Jinfengopteryx elegans_ (2005)
1. _Juravenator starki_ (2006)
1. _Sinocalliopteryx gigas_ (2007)
1. _Velociraptor mongoliensis_ (inferred 2007: quill knobs)
1. _Epidexipteryx hui_ (2008)
1. _Similicaudipteryx yixianensis_ (inferred 2008: pygostyle; confirmed 2010)
1. _Zhongornis haoae_ (2008)

1. _Tianyulong confuciusi_? (2009)
1. _Concavenator corcovatus_? (inferred 2010: quill knobs?)

1. _Yutyrannus huali_ (2012)
1. _Microraptor hanqingi_ (2012)
1. _Ornithomimus edmontonicus_ (2012)
1. _Ningyuansaurus wangi_ (2012)
1. _Eosinopteryxbrevipenna_ (2013)
1. _Citipati osmolskae_ (inferred 2013: pygostyle)
1. _Conchoraptor gracilis_ (inferred 2013: pygostyle)
1. _Jianchangosaurus yixianensis_ (2013)
1. _Aurornis xui_ (2013; possibly avialan)
1. _Changyuraptor yangi_ (2014)
1. _Kulindadromeus zabaikalicus_? (2014)
1. _Citipati osmolskae_ (inferred 2014: pygostyle)
1. _Conchoraptor gracilis_ (inferred 2014: pygostyle)
1. _Deinocheirus mirificus_ (inferred 2014: pygostyle)
1. _Yi qi_ (2015)

- Note, filamentous structures in some ornithischian dinosaurs (_Psittacosaurus_, _Tianyulong_) and pterosaurs may or may not be homologous with the feathers and protofeathers of theropods.

## Related pages

- Avialae
- Dinobird
- Coelurosaur