Avialae

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Avialans
Temporal range: Middle Jurassic–Present, 150.8–0  Ma [1]
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Earliest 165 Ma if Anchiornithidae are members [2]
Jeholornis prima NMNS.jpg
Fossil specimen of Jeholornis prima
A special composite of birds.jpg
Collage of four extant birds. Clockwise from top-left: Spanish imperial eagle (Aquila adalberti), common ostrich (Struthio camelus), mallard (Anas platyrhynchos), and common kingfisher (Alcedo atthis)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Pennaraptora
Clade: Paraves
Clade: Avialae
Gauthier, 1986
Subgroups

Avialae ("bird wings") is a clade containing the only living dinosaurs, the birds, and their ancestors. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to deinonychosaurs, though alternative definitions are occasionally used (see below).

Contents

Archaeopteryx lithographica , from the late Jurassic Period Solnhofen Formation of Germany, is usually considered the earliest known avialan which may have had the capability of powered flight, [4] a minority of studies have suggested that it might have been a deinonychosaur instead. [5] Several older (but non flight-capable) possible avialans are known from the late Jurassic Tiaojishan Formation of China, dated to about 160 million years ago. [6] [7]

Definition

Most researchers define Avialae as branch-based clade, though definitions vary. Many authors have used a definition similar to "all theropods closer to birds than to Deinonychus ." [8] [9] A nearly identical definition, "the theropod group that includes all taxa closer to Passer than to Dromaeosaurus ", was used by Agnolín and Novas (2013) for their clade Averaptora, operating under the assumption that troodontids and birds were more closely related to each other than to dromaeosaurs. They also redefine Avialae as the smallest clade containing Archaeopteryx and modern birds. [10]

Additionally, beginning in the late 2000s and early 2010s, several groups of researchers began adding the genus Troodon as an additional specifier in the definition of Avialae. Troodon had long been considered a close relative of the dromaeosaurids in the larger group Deinonychosauria, though some contemporary studies found it and other troodontids more closely related to modern birds, and so it has been specifically excluded from Avialae in more recent studies. [11]

Avialae is also occasionally defined as an apomorphy-based clade (that is, one based on derived characteristics that were not present among lineage predecessors). Jacques Gauthier, who named Avialae in 1986, re-defined it in 2001 as all dinosaurs that possessed feathered wings used in flapping flight, and the birds that descended from them. [12] [13]

Differentiation from Aves

Gauthier and de Queiroz [13] (page 34) identified four conflicting ways of defining the term "Aves", which is a problem since the same biological name is being used four different ways. They proposed a solution, number 4 below, which is to reserve the term Aves only for the crown group, the last common ancestor of all living birds and all of its descendants. Other definitions of Aves found in literature were reassigned to other clade names.

  1. Aves can mean all reptiles closer to birds than to crocodiles (alternatively Avemetatarsalia [=Panaves])
  2. Aves can mean those advanced archosaurs with feathers (alternatively Avifilopluma)
  3. Aves can mean those feathered dinosaurs that can fly (alternately Avialae)
  4. Aves can mean the last common ancestor of all the currently living birds and all of its descendants (a "crown group"). (alternatively Neornithes)

Under the fourth definition Archaeopteryx is an avialan, and not a member of Aves. Gauthier's proposals have been adopted by many researchers in the field of paleontology and bird evolution, though the exact definitions applied have been inconsistent. Avialae, initially proposed to replace the traditional fossil content of Aves, is sometimes used synonymously with the vernacular term "bird" by these researchers. [11]

Evolution

Avialae
Cladogram following the results of a phylogenetic study by Wang et al., 2016. [14]

The earliest known avialans come from the Tiaojishan Formation of China, which has been dated to the late Jurassic period (Oxfordian stage), about 160 million years ago. [11] The avialan species from this time period include Anchiornis huxleyi and Aurornis xui . Xiaotingia zhengi used to be considered a member, but was later classified within the clade Dromaeosauridae. The well-known Archaeopteryx dates from slightly later Jurassic rocks (about 155 million years old) from Germany. Many of these early avialans shared unusual anatomical features that may be ancestral to modern birds, but were later lost during bird evolution. These features include enlarged claws on the second toe which may have been held clear of the ground in life, and long feathers or "hind wings" covering the hind limbs and feet, which may have been used in aerial maneuvering. [15] It is also thought that early avialans were either cranially akinetic or had otherwise limited cranial kinesis. [16] [17]

Avialans diversified into a wide variety of forms during the Cretaceous Period. [18] Many groups retained primitive characteristics, such as clawed wings and teeth, though the latter were lost independently in a number of avialan groups, including modern birds (Aves). While the earliest forms, such as Archaeopteryx and Shenzhouraptor , retained the long bony tails of their ancestors, [18] the tails of more advanced avialans were shortened with the advent of the pygostyle bone in the group Pygostylia. In the late Cretaceous, around 95 million years ago, the ancestor of all modern birds also evolved a better sense of smell. [19]

The following cladogram is based on the analysis by Hartman et al. (2019), which found flight likely evolved five separate times among paravian dinosaurs, two of those among Avialae (in Scansoriopterygids and other avialans). Archaeopteryx and "anchiornithids" were placed in Deinonychosauria, Avialae's sister group. [5]

Paraves

In a study conducted in 2020, Archaeopteryx was recovered as an avialan. [20]

See also

Related Research Articles

<i>Archaeopteryx</i> Extinct genus of bird-like dinosaurs

Archaeopteryx, sometimes referred to by its German name, "Urvogel" is a genus of bird-like 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.

<span class="mw-page-title-main">Maniraptora</span> Clade of dinosaurs

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.

<span class="mw-page-title-main">Coelurosauria</span> Clade of dinosaurs

Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs.

<span class="mw-page-title-main">Feathered dinosaur</span> Dinosaur with feathers

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.

<span class="mw-page-title-main">Scansoriopterygidae</span> Extinct family of dinosaurs

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.

<span class="mw-page-title-main">Archaeopterygidae</span> Family of dinosaurs

Archaeopterygidae is a group of paravian dinosaurs, known from the latest Jurassic and earliest Cretaceous of Europe. In most current classifications, it contains only the genera Archaeopteryx and Wellnhoferia. As its name suggests, Protarchaeopteryx was also once referred to this group, but most paleontologists now consider it an oviraptorosaur. Other referred genera, like Jurapteryx, Wellnhoferia, and "Proornis", are probably synonymous with Archaeopteryx or do not belong into this group. Jinfengopteryx was originally described as an archaeopterygid, though it was later shown to be a troodontid. A few studies have recovered Anchiornis and Xiaotingia to also be members of the Archaeopterygidae, though most subsequent analyses have failed to arrive at the same result. Uncertainties still exist, however, and it may not be possible to confidently state whether archaeopterygids are more closely related to modern birds or to deinonychosaurs barring new and better specimens of relevant species. Teeth attributable to archaeopterygids are known from the earliest Cretaceous (Berriasian) Cherves-de-Cognac locality and the Angeac-Charente bonebed of France.

<span class="mw-page-title-main">Origin of birds</span> Evolution, adaptation, and origin of birds

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.

<i>Yandangornis</i> Extinct genus of dinosaurs

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.

<span class="mw-page-title-main">Maniraptoriformes</span> Clade of dinosaurs

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."

<span class="mw-page-title-main">Paraves</span> Clade of all dinosaurs that are more closely related to birds than to oviraptorosaurs

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.

<span class="mw-page-title-main">Avifilopluma</span> Clade including all feathered animals

Avifilopluma is a clade containing all animals with feathers. Unlike most clades, which are defined based on relative relationships, Avifilopluma is defined based on an apomorphy, that is, a unique physical characteristic shared by one group and not found outside that group. Its content is unclear, and has been speculated to range from Coelurosauria to all of Ornithodira.

<i>Epidexipteryx</i> Extinct genus of dinosaurs

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.

<i>Anchiornis</i> Extinct genus of dinosaurs

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.

<i>Xiaotingia</i> Extinct genus of dinosaurs

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.

<i>Eosinopteryx</i> Extinct genus of dinosaurs

Eosinopteryx is an extinct genus of theropod dinosaurs known to the Late Jurassic epoch of China. It contains a single species, Eosinopteryx brevipenna.

<span class="mw-page-title-main">Pennaraptora</span> Clade of dinosaurs

Pennaraptora is a clade defined as the most recent common ancestor of Oviraptor philoceratops, Deinonychus antirrhopus, and Passer domesticus, and all descendants thereof, by Foth et al., 2014.

<i>Aurornis</i> Extinct genus of dinosaurs

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.

<span class="mw-page-title-main">Anchiornithidae</span> Extinct family of dinosaurs

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.

<span class="mw-page-title-main">Biogeography of paravian dinosaurs</span> Geographic distribution of paravian dinosaurs

The biogeography of Paravian dinosaurs is the study of the global distribution of Paraves through geological history. Paraves is a clade that includes all of the Theropoda that are more closely related to birds than to oviraptorosaurs. These include Dromaeosauridae and Troodontidae and Avialae. The distribution of paraves is closely related to the evolution of the clade. Understanding the changes in their distributions may shed light on problems like how and why paraves evolve, eventually gaining the ability to fly.

References

  1. ↑ Schweigert, G. (2007). "Ammonite biostratigraphy as a tool for dating Upper Jurassic lithographic limestones from South Germany – first results and open questions" (PDF). Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 245 (1): 117–125. doi:10.1127/0077-7749/2007/0245-0117. S2CID   140597349.
  2. ↑ Zhang, H.; Wang, M.; Liu, X. (2008). "Constraints on the upper boundary age of the Tiaojishan Formation volcanic rocks in West Liaoning-North Hebei by LA-ICP-MS dating". Chinese Science Bulletin. 53 (22): 3574–3584. Bibcode:2008SciBu..53.3574Z. doi:10.1007/s11434-008-0287-4.
  3. 1 2 Cau, A.; Beyrand, V.; Voeten, D.; Fernandez, V.; Tafforeau, P.; Stein, K.; Barsbold, R.; Tsogtbaatar, K.; Currie, P.; Godefroit, P. (2017). "Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs". Nature. 552 (7685): 395–399. Bibcode:2017Natur.552..395C. doi:10.1038/nature24679. PMID   29211712. S2CID   4471941.
  4. ↑ Alonso, P. D.; Milner, A. C.; Ketcham, R. A.; Cookson, M. J.; Rowe, T. B. (2004). "The avian nature of the brain and inner ear of Archaeopteryx" (PDF). Nature . 430 (7000): 666–669. Bibcode:2004Natur.430..666A. doi:10.1038/nature02706. PMID   15295597. S2CID   4391019. Archived from the original (PDF) on 2006-02-09. Supplementary info
  5. 1 2 Hartman, Scott; Mortimer, Mickey; Wahl, William R.; Lomax, Dean R.; Lippincott, Jessica; Lovelace, David M. (2019-07-10). "A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight". PeerJ. 7: e7247. doi: 10.7717/peerj.7247 . ISSN   2167-8359. PMC   6626525 . PMID   31333906.
  6. ↑ Hu, D.; Hou, L.; Zhang, L. & Xu, X. (2009). "A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus". Nature. 461 (7264): 640–643. Bibcode:2009Natur.461..640H. doi:10.1038/nature08322. PMID   19794491. S2CID   205218015.
  7. ↑ Liu Y.-Q.; Kuang H.-W.; Jiang X.-J.; Peng N.; Xu H.; Sun H.-Y. (2012). "Timing of the earliest known feathered dinosaurs and transitional pterosaurs older than the Jehol Biota". Palaeogeography, Palaeoclimatology, Palaeoecology. 323–325: 1–12. Bibcode:2012PPP...323....1L. doi:10.1016/j.palaeo.2012.01.017.
  8. ↑ Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.) (2004). The Dinosauria, Second Edition. University of California Press., 861 pp.
  9. ↑ Senter, P (2007). "A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda)". Journal of Systematic Palaeontology. 5 (4): 429–463. Bibcode:2007JSPal...5..429S. doi:10.1017/S1477201907002143. S2CID   83726237.
  10. ↑ Federico L. Agnolín & Fernando E. Novas (2013). Avian ancestors. A review of the phylogenetic relationships of the theropods Unenlagiidae, Microraptoria, Anchiornis and Scansoriopterygidae. SpringerBriefs in Earth System Sciences. pp. 1–96. doi:10.1007/978-94-007-5637-3. ISBN   978-94-007-5636-6. S2CID   199493087.
  11. 1 2 3 Pascal Godefroit; Andrea Cau; Hu Dong-Yu; François Escuillié; Wu Wenhao; Gareth Dyke (2013). "A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds". Nature. 498 (7454): 359–62. Bibcode:2013Natur.498..359G. doi:10.1038/nature12168. PMID   23719374. S2CID   4364892.
  12. ↑ Gauthier, J. (1986). "Saurischian monophyly and the origin of birds." In: K. Padian, ed. The origin of birds and the evolution of flight. San Francisco: California, Acad.Sci. pp.1–55. (Mem.Calif.Acad.Sci.8.)
  13. 1 2 Gauthier, J., and de Queiroz, K. (2001). "Feathered dinosaurs, flying dinosaurs, crown dinosaurs, and the name Aves." Pp. 7-41 in New perspectives on the origin and early evolution of birds: proceedings of the International Symposium in Honor of John H. Ostrom (J. A. Gauthier and L. F. Gall, eds.). Peabody Museum of Natural History, Yale University, New Haven, Connecticut, U.S.A.
  14. ↑ Wang, M.; Wang, X.; Wang, Y.; Zhou, Z. (2016). "A new basal bird from China with implications for morphological diversity in early birds". Scientific Reports. 6: 19700. Bibcode:2016NatSR...619700W. doi:10.1038/srep19700. PMC   4726217 . PMID   26806355.
  15. ↑ Zheng, X.; Zhou, Z.; Wang, X.; Zhang, F.; Zhang, X.; Wang, Y.; Wei, G.; Wang, S.; Xu, X. (2013). "Hind Wings in Basal Birds and the Evolution of Leg Feathers". Science. 339 (6125): 1309–1312. Bibcode:2013Sci...339.1309Z. CiteSeerX   10.1.1.1031.5732 . doi:10.1126/science.1228753. PMID   23493711. S2CID   206544531.
  16. ↑ Wang, M.; Stidham, T.A.; Li, Z.; Xu, X.; Zhou, Z. (2021). "Cretaceous bird with dinosaur skull sheds light on avian cranial evolution". Nature Communications. 12 (1): 3890. Bibcode:2021NatCo..12.3890W. doi:10.1038/s41467-021-24147-z. PMC   8222284 . PMID   34162868.
  17. ↑ Hu, H.; Sansalone, G.; Wroe, S.; McDonald, P.G.; O'Connor, J.K.; Li, Z.; Xu, X; Zhou, Z. (2019). "Evolution of the vomer and its implications for cranial kinesis in Paraves". PNAS. 116 (39): 19571–19578. Bibcode:2019PNAS..11619571H. doi: 10.1073/pnas.1907754116 . PMC   6765239 . PMID   31501339.
  18. 1 2 Chiappe, Luis M. (2007). Glorified Dinosaurs: The Origin and Early Evolution of Birds. Sydney: University of New South Wales Press. ISBN   978-0-86840-413-4.
  19. ↑ Agency France-Presse (13 April 2011). "Birds survived dino extinction with keen senses". Cosmos Magazine. Archived from the original on 2 April 2015. Retrieved 11 June 2012.
  20. ↑ Cau, Andrea (2020-02-25). "The body plan of Halszkaraptor escuilliei (Dinosauria, Theropoda) is not a transitional form along the evolution of dromaeosaurid hypercarnivory". PeerJ. 8: e8672. doi: 10.7717/peerj.8672 . ISSN   2167-8359. PMC   7047864 . PMID   32140312.
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