Feathered dinosaur

A feathered dinosaur is any species of dinosaur possessing feathers. That includes all species of birds, but there is a hypothesis that many, if not all non-avian dinosaur species also possessed feathers in some shape or form. That theory has been challenged by some research.[1]

Life restoration of the feathered Wulong with colors inferred from preserved melanosomes
The ostrich is the largest living dinosaur.

It has been suggested that feathers had originally functioned as thermal insulation, as it remains their function in the down feathers of infant birds today prior to their eventual modification in birds into structures that support flight.

Since scientific research began on dinosaurs in the early 1800s, they were generally believed to be closely related to modern reptiles such as lizards. The word dinosaur itself, coined in 1842 by paleontologist Richard Owen, comes from the Greek for 'terrible lizard'. That view began to shift during the so-called dinosaur renaissance in scientific research in the late 1960s, and by the mid-1990s, significant evidence had emerged that dinosaurs were much more closely related to birds, which descended directly from the theropod group of dinosaurs.[2]

Knowledge of the origin of feathers developed as new fossils were discovered throughout the 2000s and the 2010s, and technology enabled scientists to study fossils more closely. Among non-avian dinosaurs, feathers or feather-like integument have been discovered in dozens of genera via direct and indirect fossil evidence.[3] Although the vast majority of feather discoveries have been in coelurosaurian theropods, feather-like integument has also been discovered in at least three ornithischians, suggesting that feathers may have been present on the last common ancestor of the Ornithoscelida, a dinosaur group including both theropods and ornithischians.[4] It is possible that feathers first developed in even earlier archosaurs, in light of the discovery of vaned feathers in pterosaurs.[5][6] Fossil feathers from the dinosaur Sinosauropteryx contain traces of beta-proteins (formerly called beta-keratins), confirming that early feathers had a composition similar to that of feathers in modern birds.[7] Crocodilians also possess beta keratin similar to those of birds, which suggests that they evolved from common ancestral genes.[8][9]

History of research

Early

The Berlin Archaeopteryx

Shortly after the 1859 publication of Charles Darwin's On the Origin of Species, the British biologist Thomas Henry Huxley proposed that birds were descendants of dinosaurs. He compared the skeletal structure of Compsognathus, a small theropod dinosaur, and the "first bird" Archaeopteryx lithographica (both of which were found in the Upper Jurassic Bavarian limestone of Solnhofen). He showed that, apart from its hands and feathers, Archaeopteryx was quite similar to Compsognathus. Thus Archaeopteryx represents a transitional fossil. In 1868, he published On the Animals which are most nearly intermediate between Birds and Reptiles, which made that case.[10][11]

The first restoration of a feathered dinosaur was Huxley's depiction in 1876 of a feathered Compsognathus, made to accompany a bird evolution lecture he delivered in New York, in which he speculated that the aforementioned dinosaur might have had feathers.[12]

Dinosaur renaissance

A century later, during the dinosaur renaissance, paleoartists began to create modern restorations of highly active dinosaurs. In 1969, Robert T. Bakker drew a running Deinonychus. His student Gregory S. Paul depicted non-avian maniraptoran dinosaurs with feathers and protofeathers, starting in the late 1970s. [13]

Fossil discoveries

Cast in Japan of a resting trace from Massachusetts, which was argued to have been made by a theropod like Dilophosaurus and to include feather impressions around the belly (arrow), but that has been questioned.

The first known specimen of Archaeopteryx, on the basis of which the genus was named, was an isolated feather, although whether or not it belongs to Archaeopteryx has been controversial.[14][15] One of the earliest discoveries of possible feather impressions by non-avian dinosaurs is a trace fossil (Fulicopus lyellii) of the 195–199 million year old Portland Formation in the northeastern United States. Gierlinski (1996, 1997, 1998) and Kundrát (2004) have interpreted traces between two footprints in this fossil as feather impressions from the belly of a squatting dilophosaurid. Although some reviewers have raised questions about the naming and interpretation of this fossil, if correct, that early Jurassic fossil is the oldest known evidence of feathers, almost 30 million years older than the next-oldest-known evidence.[16][17][18]

Sinosauropteryx fossil, the first fossil of a definitively non-avialan dinosaur with feathers

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. Turner et al. (2007) reported quill knobs from an ulna of Velociraptor mongoliensis, and these are strongly correlated with large and well-developed secondary feathers.[19]

A nesting Citipati osmolskae specimen, at the AMNH

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.[20] Although no feathers were preserved, it is likely that these would have been present to insulate eggs and juveniles.[21]

Fossil of Microraptor gui includes impressions of feathered wings (see arrows)

Not all of the Chinese fossil discoveries proved valid however. In 1999, a supposed fossil of an apparently feathered dinosaur named Archaeoraptor liaoningensis, also found in Liaoning, turned out to be a forgery. Comparing the photograph of the specimen with another find, Chinese paleontologist Xu Xing came to the conclusion that it was composed of two portions of different fossil animals. His claim made National Geographic review their research and they too came to the same conclusion.[22]

In 2011, samples of amber were discovered to contain preserved feathers from 75 to 80 million years ago during the Cretaceous era, 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.[23][24] More complex feathers were revealed to have variations in coloration similar to modern birds, while simpler protofeathers were predominantly dark. Only 11 specimens are currently known. The specimens are too rare to be broken open to study their melanosomes (pigment-bearing organelles), but there are plans for using non-destructive high-resolution X-ray imaging.[25] Melanosomes produce colouration in feathers; as differently-shaped melanosomes produce different colours, subsequent research on melanosomes preserved in feathered dinosaur specimens has led to reconstructions of the life appearance of several dinosaur species. These include Anchiornis,[26] Sinosauropteryx,[27] Microraptor,[28] and Archaeopteryx.[15]

In 2016, the discovery was announced of a feathered dinosaur tail preserved in amber that is estimated to be 99 million years old. Lida Xing, a researcher from the China University of Geosciences in Beijing, found the specimen at an amber market in Myanmar. It is the first definitive discovery of dinosaur material in amber.[29][30][31][32]

Current knowledge

Non-avian dinosaur species preserved with evidence of feathers

Fossil of Sinornithosaurus millenii, the first evidence of feathers in dromaeosaurids
Cast of a Caudipteryx fossil with feather impressions and stomach content
Fossil cast of a Sinornithosaurus millenii

Several non-avian dinosaurs are now known to have been feathered. Direct evidence of feathers exists for several species. In all examples, the evidence described consists of feather impressions, except those genera inferred to have had feathers based on skeletal or chemical evidence, such as 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).[33]

Primitive feather types

Integumentary structures that gave rise to the feathers of birds are seen in the dorsal spines of reptiles and fish. A similar stage in their evolution to the complex coats of birds and mammals can be observed in living reptiles such as iguanas and Gonocephalus agamids. Feather structures are thought to have proceeded from simple hollow filaments through several stages of increasing complexity, ending with the large, deeply rooted feathers with strong pens (rachis), barbs and barbules that birds display today.[34]

According to Prum's (1999) proposed model, at stage I, the follicle originates with a cylindrical epidermal depression around the base of the feather papilla. The first feather resulted when undifferentiated tubular follicle collar developed out of the old keratinocytes being pushed out. At stage II, the inner, basilar layer of the follicle collar differentiated into longitudinal barb ridges with unbranched keratin filaments, while the thin peripheral layer of the collar became the deciduous sheath, forming a tuft of unbranched barbs with a basal calamus. Stage III consists of two developmental novelties, IIIa and IIIb, as either could have occurred first. Stage IIIa involves helical displacement of barb ridges arising within the collar. The barb ridges on the anterior midline of the follicle fuse together, forming the rachis. The creation of a posterior barb locus follows, giving an indeterminate number of barbs. This resulted in a feather with a symmetrical, primarily branched structure with a rachis and unbranched barbs. In stage IIIb, barbules paired within the peripheral barbule plates of the barb ridges, create branched barbs with rami and barbules. This resulting feather is one with a tuft of branched barbs without a rachis. At stage IV, differentiated distal and proximal barbules produce a closed, pennaceous vane (a contour feather). A closed vane develops when pennulae on the distal barbules form a hooked shape to attach to the simpler proximal barbules of the adjacent barb. Stage V developmental novelties gave rise to additional structural diversity in the closed pennaceous feather. Here, asymmetrical flight feathers, bipinnate plumulaceous feathers, filoplumes, powder down, and bristles evolved.[35]

Some evidence suggests that the original function of simple feathers was insulation. In particular, preserved patches of skin in large, derived, tyrannosauroids show scutes, while those in smaller, more primitive, forms show feathers. This may indicate that the larger forms had complex skins, with both scutes and filaments, or that tyrannosauroids may be like rhinos and elephants, having filaments at birth and then losing them as they developed to maturity.[36] An adult Tyrannosaurus rex weighed about as much as an African elephant. If large tyrannosauroids were endotherms, they would have needed to radiate heat efficiently.[37] This is due to the different structural properties of feathers compared to fur.[38]

Some evidence also suggests that more derived feather types may have served as insulation. For instance, a study of oviraptor pennaceous wing feathers and nesting posture suggests that elongated wing feathers evidently may have served to fill gaps between brooding individuals' insulatory body chamber and the outside environment. This "wall" of wing feathers could have shielded eggs from temperature extremes.[39]

There is an increasing body of evidence that supports the display hypothesis, which states that early feathers were colored and increased reproductive success.[40][41] Coloration could have provided the original adaptation of feathers, implying that all later functions of feathers, such as thermoregulation and flight, were co-opted.[40] This hypothesis has been supported by the discovery of pigmented feathers in multiple species.[42][43][44][45] Supporting the display hypothesis is the fact that fossil feathers have been observed in a ground-dwelling herbivorous dinosaur clade, making it unlikely that feathers functioned as predatory tools or as a means of flight.[46] Additionally, some specimens have iridescent feathers.[47] Pigmented and iridescent feathers may have provided greater attractiveness to mates, providing enhanced reproductive success when compared to non-colored feathers.[48] Current research shows that it is plausible that theropods would have had the visual acuity necessary to see the displays. In a study by Stevens (2006), the binocular field of view for Velociraptor has been estimated to be 55 to 60 degrees, which is about that of modern owls. Visual acuity for Tyrannosaurus has been predicted to be anywhere from about that of humans to 13 times that of humans.[49] Paleontological and evolutionary developmental studies show that feathers or feather-like structures were converting back to scales.[50][51][52]

The idea that precursors of feathers appeared before they were co-opted for insulation is already stated in Gould and Vrba (1982).[53] The original benefit might have been metabolic. Feathers are largely made of the keratin protein complex, which has disulfide bonds between amino acids that give it stability and elasticity. The metabolism of amino acids containing sulfur can be toxic; however, if the sulfur amino acids are not catabolized as the final products of urea or uric acid but used for the synthesis of keratin instead, the release of hydrogen sulfide is extremely reduced or avoided. For an organism whose metabolism works at high internal temperatures of 40 °C (104 °F) or greater, it can be extremely important to prevent the excess production of hydrogen sulfide. This hypothesis could be consistent with the need for high metabolic rate of theropod dinosaurs.[54][55]

The point is not known with certainty in archosaur phylogeny that the earliest simple "protofeathers" arose, as well as whether they arose once or independently multiple times. Filamentous structures are clearly present in pterosaurs,[56] and long, hollow quills have been reported in specimens of the ornithischian dinosaurs Psittacosaurus and Tianyulong[57][58] although there has been disagreement.[59][60][61] In 2009, Xu et al. noted that the hollow, unbranched, stiff integumentary structures found on a specimen of Beipiaosaurus were strikingly similar to the integumentary structures of Psittacosaurus and pterosaurs. They suggested that all of these structures may have been inherited from a common ancestor much earlier in the evolution of archosaurs, possibly in an ornithodire from the Middle Triassic or earlier.[62] More recently, findings in Russia of the basal neornithischian Kulindadromeus report that although the lower leg and tail seemed to be scaled, "varied integumentary structures were found directly associated with skeletal elements, supporting the hypothesis that simple filamentous feathers, as well as compound feather-like structures comparable to those in theropods, were widespread amongst the whole dinosaur clade."[63] In contrast, a 2016 study published in the Journal of Geology suggested that the integumentary structures found on Kulindadromeus and Psittacosaurus may be highly deformed scales rather than filamentous feathers.[59]

Display feathers are also known from dinosaurs that are very primitive members of the bird lineage, or Avialae. The most primitive example is Epidexipteryx, which had a short tail with extremely long, ribbon-like feathers. Oddly enough, the fossil does not preserve wing feathers, suggesting that Epidexipteryx was either secondarily flightless, or that display feathers evolved before flight feathers in the bird lineage.[64] Plumaceous feathers are found in nearly all lineages of Theropoda common in the northern hemisphere, and pennaceous feathers are attested as far down the tree as the Ornithomimosauria. The fact that only adult Ornithomimus had wing-like structures suggests that pennaceous feathers evolved for mating displays.[65]

Phylogeny and inference of feathers in other dinosaurs

Cladogram showing distribution of feathers in Dinosauria, as of 2019. The groups that are marked with scales did not necessarily lack feathers but simply have never been found with feather impressions.

This technique, called phylogenetic bracketing, can also be used to infer the type of feathers a species may have had, since the developmental history of feathers is now reasonably well-known. All feathered species had filamentaceous or plumaceous (downy) feathers, with pennaceous feathers found among the more bird-like groups. The following cladogram is adapted from Godefroit et al., 2013.[66]

Grey denotes a clade that is not known to contain any feathered specimen at the time of writing, some of which have fossil evidence of scales. The presence or lack of feathered specimens in a given clade does not confirm that all members in a clade have the specified integument, unless corroborated with representative fossil evidence within clade members.

Neotheropoda

Dilophosauridae

Orionides

Megalosauroidea

Avetheropoda

Carnosauria

Coelurosauria

Sciurumimus – filamentous feathers

Tyrannoraptora

Tyrannosauroidea (Dilong, Yutyrannus) – plumulaceous feathers

Sinocalliopteryx – plumulaceous feathers

Compsognathidae (Sinosauropteryx, GMV 2124) – plumulaceous feathers

Juravenator – filamentous feathers

Ornitholestes

Maniraptoriformes

Ornithomimosauria (Ornithomimus, Deinocheirus) – plumulaceous feathers

Maniraptora

Alvarezsauridae (Shuvuuia) – plumulaceous feathers

Therizinosauroidea (Beipiaosaurus, Jianchangosaurus) – plumulaceous feathers

Pennaraptora

Oviraptorosauria (Avimimus, Nomingia, Caudipteryx, Similicaudipteryx, Protarchaeopteryx, Ningyuansaurus, Citipati, Conchoraptor) – pennaceous feathers

Paraves

Scansoriopterygidae (Scansoriopteryx, Epidexipteryx) – pennaceous feathers

Eosinopteryx – pennaceous feathers

Eumaniraptora

Dromaeosauridae (Sinornithosaurus, Microraptor, Velociraptor, Changyuraptor) – pennaceous feathers

Troodontidae (Jinfengopteryx) – pennaceous feathers

Avialae (ancestors of birds)

The following cladogram is from Xu (2020).[67]

  1. Slender monofilamentous integument
  2. Broad monofilamentous integument
  3. Basally joining filamentous feather
  4. Basally joining shafter filamentous feather
  5. Radially branched shafted filamentous feather
  6. Bilaterally branched filamentous feather
  7. Basally joining branched filamentous feather
  8. Basally joining membranous-based filamentous feather
  9. Symmetrical open-vaned feather
  10. Symmetrical close-vaned feather
  11. Asymmetrical close-vaned feather
  12. Proximally ribbon-like close-vaned feather
  13. Rachis-dominant close-vaned feather

crocodiles and relatives

Ornithodira

Pterosauria 1?

Dinosauria
Ornithischia

Heterodontosaurus

Tianyulong 1?

Kulindadromeus 1? ,3?

Psittacosaurus 1

Triceratops

Sauropodomorpha

Coelophysis

Sciurumimus 1

Concavenator

Coelurosauria

Yutyrannus 2, 3?, 4?, 5? 6?

Dilong 3?, 4?, 5?, 6?

Tyrannosaurus

Ornithomimus edmontonicus 1?, 2?, 3?

Maniraptora

Sinosauropteryx 3?, 4, 5?, 6?

Beipiaosaurus 2, 3?, 4?, 5?, 6?

Therizinosaurus

Haplocheirus

Shuvuuia 1?

Pennaraptora

Protarchaeopteryx 3?, 4?, 5?, 6?, 9?, 10

Incisivosaurus 3?, 4?, 5?, 6?, 10, 12

Paraves

Epidexipteryx 3?, 4?, 5?, 6?, 8, 13

Yi 3?, 4?, 5?, 6?, 7

Avialae (most types)

Anchiornis 3?, 4? 5?, 6?, 7?, 10

Jianianhualong 3?, 4?, 5?, 6?, 10, 11

Microraptor 3?, 4?, 5?, 6?, 10, 11

Sinornithosaurus 3, 4, 5?, 6?, 10

See also

References

  1. Bell, Phill R. (January 2014). "A review of hadrosaur skin impressions".
  2. Brown, Joseph W.; Van Tuinen, M. (2011). "Evolving Perceptions on the Antiquity of the Modern Avian Tree". Living Dinosaurs. pp. 306–324. doi:10.1002/9781119990475.ch12. ISBN 9781119990475.
  3. Farago, Jason (7 March 2019). "T. Rex Like You Haven't Seen Him: With Feathers". The New York Times. Retrieved 7 March 2019.
  4. Baron, Matthew G.; Norman, David B.; Barrett, Paul M. (23 March 2017). "A new hypothesis of dinosaur relationships and early dinosaur evolution". Nature. 543 (7646): 501–506. Bibcode:2017Natur.543..501B. doi:10.1038/nature21700. PMID 28332513. S2CID 205254710.
  5. Michael Benton, A colourful view of the origin of dinosaur feathers. Nature 604, 630-631 (2022)
  6. Cincotta, A., Nicolaï, M., Campos, H.B.N. et al. Pterosaur melanosomes support signalling functions for early feathers. Nature 604, 684–688 (2022). https://doi.org/10.1038/s41586-022-04622-3
  7. Slater, Tiffany S.; Edwards, Nicholas P.; Webb, Samuel M.; Zhang, Fucheng; McNamara, Maria E. (21 September 2023). "Preservation of corneous β-proteins in Mesozoic feathers". Nature Ecology & Evolution. 7 (10): 1706–1713. doi:10.1038/s41559-023-02177-8. ISSN 2397-334X.
  8. Greenwold, Matthew J.; Sawyer, Roger H. (September 2013). "Molecular evolution and expression of archosaurian β-keratins: Diversification and expansion of archosaurian β-keratins and the origin of feather β-keratins". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 320 (6): 393–405. doi:10.1002/jez.b.22514. PMID 23744807.
  9. Alibardi, L.; Knapp, L. W.; Sawyer, R. H. (1 June 2006). "Beta-keratin localization in developing alligator scales and feathers in relation to the development and evolution of feathers". Journal of Submicroscopic Cytology and Pathology. 38 (2–3): 175–192. ISSN 1122-9497. PMID 17784647.
  10. Huxley, T.H. (1868). "On the animals which are most nearly intermediate between birds and reptiles". Annals and Magazine of Natural History. 4th. 2: 66–75.
  11. Foster, Michael; Lankester, E. Ray 1898–1903. The scientific memoirs of Thomas Henry Huxley. 4 vols and supplement. London: Macmillan.
  12. Huxley, Thomas Henry (1877). "The Hypothesis of Evolution. The Neutral and the Favourable Evidence.". In Huxley, Thomas Henry (ed.). American Addresses, With A Lecture on Biology. New York: D. Appleton And Company.
  13. "1970s: Dinosaurs Redesigned". Paleoartistry. Retrieved 15 June 2017.
  14. Kaye, T. G.; Pittman, M.; Mayr, G.; Schwarz, D.; Xu, X. (2019). "Detection of lost calamus challenges identity of isolated Archaeopteryx feather". Scientific Reports. 9 (1): 1182. Bibcode:2019NatSR...9.1182K. doi:10.1038/s41598-018-37343-7. PMC 6362147. PMID 30718905.
  15. Carney, R. M.; Tischlinger, H.; Shawkey, M. D. (2020). "Evidence corroborates identity of isolated fossil feather as a wing covert of Archaeopteryx". Scientific Reports. 10 (1): 15593. Bibcode:2020NatSR..1015593C. doi:10.1038/s41598-020-65336-y. PMC 7528088. PMID 32999314.
  16. Gierliński, G. (1996). "Feather-like impressions in a theropod resting trace from the Lower Jurassic of Massachusetts". Museum of Northern Arizona Bulletin. 60: 179–184.
  17. Kundrát, Martin (15 July 2004). "When did theropods become feathered?-evidence for pre-archaeopteryx feathery appendages". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 302B (4): 355–364. doi:10.1002/jez.b.20014. PMID 15287100.
  18. Tetrapod Zoology, ScienceBlogs
  19. Turner, A. H.; Makovicky, P. J.; Norell, M. A. (21 September 2007). "Feather Quill Knobs in the Dinosaur Velociraptor". Science. 317 (5845): 1721. Bibcode:2007Sci...317.1721T. doi:10.1126/science.1145076. PMID 17885130.
  20. Norell, M. A.; Clark, J. M.; Chiappe, L. M.; Dashzeveg, D. (1995). "A nesting dinosaur". Nature. 378 (6559): 774–776. Bibcode:1995Natur.378..774N. doi:10.1038/378774a0. S2CID 4245228.
  21. Hopp, Thomas P.; Orsen, Mark J. (2004). "Dinosaur Brooding Behavior and the Origin of Flight Feathers". In Currie, Philip J.; Koppelhus, Eva B.; Shugar, Martin A.; Wright, Joanna L. (eds.). Feathered Dragons: Studies on the Transition from Dinosaurs to Birds. Indiana University Press. pp. 234–250. ISBN 978-0-253-34373-4.
  22. "Transcript: The Dinosaur that Fooled the World". BBC. Retrieved 22 December 2006.
  23. Bock, Walter J. (August 2000). "Explanatory History of the Origin of Feathers1". American Zoologist. 40 (4): 478–485. doi:10.1668/0003-1569(2000)040[0478:ehotoo]2.0.co;2. S2CID 198155047.
  24. Chung, Emily (12 September 2011). "Dinosaur feathers found in Alberta amber". Canadian Broadcasting Corporation. Retrieved 16 September 2011.
  25. Switek, Brian (15 September 2011). "Amber inclusions showcase prehistoric feathers". Nature. doi:10.1038/news.2011.539.
  26. Li, Q.; Gao, K.-Q.; Vinther, J.; Shawkey, M. D.; Clarke, J. A.; D'Alba, L.; Meng, Q.; Briggs, D. E. G.; Prum, R. O. (2010). "Plumage Color Patterns of an Extinct Dinosaur" (PDF). Science. 327 (5971): 1369–1372. Bibcode:2010Sci...327.1369L. doi:10.1126/science.1186290. PMID 20133521. S2CID 206525132.
  27. Smithwick, F. M.; Nicholls, R.; Cuthill, I. C.; Vinther, J. (2017). "Countershading and Stripes in the Theropod Dinosaur Sinosauropteryx Reveal Heterogeneous Habitats in the Early Cretaceous Jehol Biota". Current Biology. 27 (21): 3337–3343.e2. doi:10.1016/j.cub.2017.09.032. PMID 29107548.
  28. Li, Q.; Gao, K.-Q.; Meng, Q.; Clarke, J. A.; Shawkey, M. D.; D'Alba, L.; Pei, R.; Ellison, M.; Norell, M. A.; Vinther, J. (2012). "Reconstruction of Microraptor and the Evolution of Iridescent Plumage" (PDF). Science. 335 (6073): 1215–1219. Bibcode:2012Sci...335.1215L. doi:10.1126/science.1213780. PMID 22403389. S2CID 206537426. Archived from the original (PDF) on 31 August 2018.
  29. St. Fleur, Nicholas (8 December 2016). "That Thing With Feathers Trapped in Amber? It Was a Dinosaur Tail". The New York Times. Retrieved 8 December 2016.
  30. Romey, Kristin (8 December 2016). "First Dinosaur Tail Found Preserved in Amber". National Geographic Society. Retrieved 12 December 2016.
  31. Rincon, Paul (8 December 2016). "'Beautiful' dinosaur tail found preserved in amber". BBC News. Retrieved 8 December 2016.
  32. Xing, Lida; McKellar, Ryan C.; Xu, Xing; Li, Gang; Bai, Ming; Persons, W. Scott; Miyashita, Tetsuto; Benton, Michael J.; Zhang, Jianping; Wolfe, Alexander P.; Yi, Qiru; Tseng, Kuowei; Ran, Hao; Currie, Philip J. (December 2016). "A Feathered Dinosaur Tail with Primitive Plumage Trapped in Mid-Cretaceous Amber". Current Biology. 26 (24): 3352–3360. doi:10.1016/j.cub.2016.10.008. PMID 27939315.
  33. Stephen L. Brusatte; Graeme T. Lloyd; Steve C. Wang; Mark A. Norell (2014). "Gradual assembly of avian body plan culminated in rapid rates of evolution across the dinosaur-bird transition". Current Biology. 24 (20): 2386–2392. doi:10.1016/j.cub.2014.08.034. PMID 25264248.
  34. Prum, R. & Brush A.H.; Brush (2002). "The evolutionary origin and diversification of feathers". The Quarterly Review of Biology. 77 (3): 261–295. doi:10.1086/341993. PMID 12365352. S2CID 6344830.
  35. Prum, R (1999). "Development and evolutionary origin of feathers". Journal of Experimental Zoology. 285 (4): 291–306. doi:10.1002/(SICI)1097-010X(19991215)285:4<291::AID-JEZ1>3.0.CO;2-9. PMID 10578107.
  36. Xu, Xing; Norell, Mark A.; Kuang, Xuewen; Wang, Xiaolin; Zhao, Qi; Jia, Chengkai (October 2004). "Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids" (PDF). Nature. 431 (7009): 680–684. Bibcode:2004Natur.431..680X. doi:10.1038/nature02855. PMID 15470426. S2CID 4381777.
  37. Norell, M. Xu, X. (2005) "The Varieties of Tyrannosaurs", Natural History Magazine, May 2005.
  38. Dawson, T. J.; Maloney, S. K. (2013). "Fur versus feathers: the different roles of red kangaroo fur and emu feathers in thermoregulation in the Australian arid zone". Australian Mammalogy. 26 (2): 145. doi:10.1071/am04145.
  39. Orsen, M. J.; Hopp, T. P. (2004). Feathered dragons: studies on the transition from dinosaurs to birds. Indiana University Press. pp. 234–350.
  40. Dimond, C. C.; R. J. Cabin; J. S. Brooks (2011). "Feathers, Dinosaurs, and Behavioral Cues: Defining the Visual Display Hypothesis for the Adaptive Function of Feathers in Non-Avian Theropods". BIOS. 82 (3): 58–63. doi:10.1893/011.082.0302. S2CID 98221211.
  41. Sumida, S. S.; C. A. Brochu (2000). "Phylogenetic Context for the Origin of Feathers". American Zoologist. 40 (4): 485–503. doi:10.1093/icb/40.4.486.
  42. Lingham-Soliar, T. (2011). "The evolution of the feather: Sinosauropteryx, a colourful tail". Journal of Ornithology. 152 (3): 567–577. doi:10.1007/s10336-010-0620-y. S2CID 29827649.
  43. Vinther, J.; D. E. G. Briggs; R. O. Prum & V. Saranathan (2008). "The colour of fossil feathers". Biology Letters. 4 (5): 522–525. doi:10.1098/rsbl.2008.0302. PMC 2610093. PMID 18611841.
  44. Zhang, F. C.; S. L. Kearns; P. J. Orr; M. J. Benton; Z. H. Zhou; D. Johnson; X. Xu; X. L. Wang (2010). "Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds" (PDF). Nature. 463 (7284): 1075–1078. Bibcode:2010Natur.463.1075Z. doi:10.1038/nature08740. PMID 20107440. S2CID 205219587.
  45. Li, Q.; Gao, K.; Vinther, J.; Shawkey, M. D.; Clarke, J. A.; D'Alba, L.; Meng, Q. (2010). "Plumage Color Patterns of an Extinct Dinosaur" (PDF). Science. 327 (5971): 1369–1372. Bibcode:2010Sci...327.1369L. doi:10.1126/science.1186290. PMID 20133521. S2CID 206525132.
  46. Zelenitsky, Darla K.; Therrien, Francois; Erickson, Gregory M.; DeBuhr, Christopher L.; Kobayashi, Yoshitsugu; Eberth, David A.; Hadfield, Frank (2012). "Feathered Non-Avian Dinosaurs From North America Provide Insight into Wing Origins". Science. 338 (6106): 510–514. Bibcode:2012Sci...338..510Z. doi:10.1126/science.1225376. PMID 23112330. S2CID 2057698.
  47. Li, Q. G.; K. Q. Gao; Q. J. Meng; M. D. Shawkey; L. D'Alba; R. Pei; M. Ellison; M. A. Norell; J. Vinther (2012). "Reconstruction of Microraptor and the Evolution of Iridescent Plumage". Science. 335 (6073): 1215–1219. Bibcode:2012Sci...335.1215L. doi:10.1126/science.1213780. PMID 22403389. S2CID 206537426.
  48. Dimond, C. C.; Cabin, R. J.; Brooks, J. S. (2011). "Feathers, Dinosaurs, and Behavioral Cues: Defining the Visual Display Hypothesis for the Adaptive Function of Feathers in NonAvian Theropods". BIOS. 82 (3): 58–63. doi:10.1893/011.082.0302. S2CID 98221211.
  49. Rauhut, Oliver W. M.; Foth, Christian; Tischlinger, Helmut; Norell, Mark A. (17 July 2012). "Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany". Proceedings of the National Academy of Sciences of the United States of America. 109 (29): 11746–11751. Bibcode:2012PNAS..10911746R. doi:10.1073/pnas.1203238109. PMC 3406838. PMID 22753486.
  50. Dhouailly, Danielle (20 April 2009). "A new scenario for the evolutionary origin of hair, feather, and avian scales". Journal of Anatomy. 214 (4): 587–606. doi:10.1111/j.1469-7580.2008.01041.x. PMC 2736124. PMID 19422430.
  51. Bell, Phil R.; Campione, Nicolás E.; Persons, W. Scott; Currie, Philip J.; Larson, Peter L.; Tanke, Darren H.; Bakker, Robert T. (30 June 2017). "Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution". Biology Letters. 13 (6): 20170092. doi:10.1098/rsbl.2017.0092. PMC 5493735. PMID 28592520.
  52. Zheng, Xiaoting; Zhou, Zhonghe; Wang, Xiaoli; Zhang, Fucheng; Zhang, Xiaomei; Wang, Yan; Wei, Guangjin; Wang, Shuo; Xu, Xing (15 March 2013). "Hind Wings in Basal Birds and the Evolution of Leg Feathers". Science. 339 (6125): 1309–1312. Bibcode:2013Sci...339.1309Z. doi:10.1126/science.1228753. ISSN 0036-8075. PMID 23493711. S2CID 206544531.
  53. Gould, Stephen J.; Vrba, Elisabeth S. (1982). "Exaptation: a missing term in the science of form" (PDF). Paleobiology. 8 (1): 4–15. Bibcode:1982Pbio....8....4G. doi:10.1017/S0094837300004310. S2CID 86436132.
  54. Reichholf, J. H. (1996). "Die Feder, die Mauser und der Ursprung der Vögel. Ein neure Sicht zur Evolution der Vögel" [The feather, the moult and the origin of the birds. A new perspective on the evolution of birds]. Archaeopteryx (in German). 14: 27–38.
  55. Bock, Walter J. (1 August 2000). "Explanatory History of the Origin of Feathers". American Zoologist. 40 (4): 478–485. CiteSeerX 10.1.1.497.1279. doi:10.1093/icb/40.4.478.
  56. Yang, Z.; Jiang, B.; McNamara, M. E.; Kearns, S. L.; Pittman, M.; Kaye, T. G.; Orr, P. J.; Xu, X.; Benton, M. J. (2019). "Pterosaur integumentary structures with complex feather-like branching" (PDF). Nature Ecology & Evolution. 3 (1): 24–30. doi:10.1038/s41559-018-0728-7. hdl:1983/1f7893a1-924d-4cb3-a4bf-c4b1592356e9. PMID 30568282. S2CID 56480710.
  57. Mayr, Gerald; Peters, Stefan; Plodowski, Gerhard; Vogel, Olaf (2002). "Bristle-like integumentary structures at the tail of the horned dinosaur Psittacosaurus". Naturwissenschaften. 89 (8): 361–365. Bibcode:2002NW.....89..361M. doi:10.1007/s00114-002-0339-6. PMID 12435037. S2CID 17781405.
  58. Zheng, Xiao-Ting; You, Hai-Lu; Xu, Xing; Dong, Zhi-Ming (2009). "An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures". Nature. 458 (7236): 333–336. Bibcode:2009Natur.458..333Z. doi:10.1038/nature07856. PMID 19295609. S2CID 4423110.
  59. Qiang, Ji; Xuri, Wang; Yannan, Ji; Ball, Black (2016). "Feathers or scales". Journal of Geology (4): 535–544.
  60. Unwin, David (28 September 2020). "No protofeathers on pterosaurs". Nature Ecology and Evolution. 4 (12): 1590–1591. doi:10.1038/s41559-020-01308-9. PMID 32989266. S2CID 222168569.
  61. Barrett, Paul M.; Evans, David C.; Campione, Nicolás E. (30 June 2015). "Evolution of dinosaur epidermal structures". Biology Letters. 11 (6): 20150229. doi:10.1098/rsbl.2015.0229. PMC 4528472. PMID 26041865.
  62. Xu, X.; Zheng, X.; You, H. (2009). "A new feather type in a nonavian theropod and the early evolution of feathers". Proceedings of the National Academy of Sciences. 106 (3): 832–4. Bibcode:2009PNAS..106..832X. doi:10.1073/pnas.0810055106. PMC 2630069. PMID 19139401.
  63. Godefroit, P; Sinitsa, S; Dhouailly, D; Bolotsky, Y; Sizov, A (2013). Feather-like structures and scales in a Jurassic neornithischian dinosaur from Siberia.
  64. Zhang, Fucheng; Zhou, Zhonghe; Xu, Xing; Wang, Xiaolin; Sullivan, Corwin (2008). "A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers" (PDF). Nature. 455 (7216): 1105–1108. Bibcode:2008Natur.455.1105Z. doi:10.1038/nature07447. PMID 18948955. S2CID 4362560.
  65. Zelenitsky, D. K.; Therrien, F.; Erickson, G. M.; DeBuhr, C. L.; Kobayashi, Y.; Eberth, D. A.; Hadfield, F. (25 October 2012). "Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins". Science. 338 (6106): 510–514. Bibcode:2012Sci...338..510Z. doi:10.1126/science.1225376. PMID 23112330. S2CID 2057698.
  66. Godefroit, Pascal; Cau, Andrea; Hu, Dong-Yu; Escuillié, François; Wu, Wenhao; Dyke, Gareth (2013). "A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds". Nature. 498 (7454): 359–362. Bibcode:2013Natur.498..359G. doi:10.1038/nature12168. PMID 23719374. S2CID 4364892.
  67. Xu, Xing (2020), Foth, Christian; Rauhut, Oliver W. M. (eds.), "Filamentous Integuments in Nonavialan Theropods and Their Kin: Advances and Future Perspectives for Understanding the Evolution of Feathers", The Evolution of Feathers: From Their Origin to the Present, Fascinating Life Sciences, Cham: Springer International Publishing, pp. 67–78, doi:10.1007/978-3-030-27223-4_5, ISBN 978-3-030-27223-4, S2CID 216384668
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.