Avemetatarsalia

"Panaves" redirects here. Not to be confused with Paraves.

Avemetatarsalians
Temporal range:
Middle Triassic–Present, 247–0 Ma (possible Early Triassic record if Prorotodactylus is part of the clade[1])
Seven avemetatarsalians (top left to bottom right): a Gentoo penguin, Marasuchus, Kentrosaurus, Thalassodromeus (foreground) with Anhanguera (background), Diplodocus, Rhamphorhynchus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Sauropsida
Clade: Archosauria
Clade: Avemetatarsalia
Benton, 1999
Subgroups
Synonyms
  • Dracones Haeckel, 1895
  • Ornithosuchia Huene, 1908
  • Ornithotarsi Gauthier, 1986
  • Pan-Aves Gauthier and de Queiroz, 2001

Avemetatarsalia (meaning "bird metatarsals") is a clade of diapsid reptiles containing all archosaurs more closely related to birds than to crocodilians.[2] The two most successful groups of avemetatarsalians were the dinosaurs and pterosaurs. Dinosaurs were the largest terrestrial animals for much of the Mesozoic Era, and one group of small feathered dinosaurs (Aves, i.e. birds) has survived up to the present day. Pterosaurs were the first flying vertebrates and persisted through the Mesozoic before dying out at the Cretaceous-Paleogene (K-Pg) extinction event. Both dinosaurs and pterosaurs appeared in the Triassic Period, shortly after avemetatarsalians as a whole.[2][3] The name Avemetatarsalia was first established by British palaeontologist Michael Benton in 1999. An alternate name is Pan-Aves, or "all birds", in reference to its definition containing all animals, living or extinct, which are more closely related to birds than to crocodilians.[4]

Although dinosaurs and pterosaurs were the only avemetatarsalians to survive past the end of the Triassic, other groups flourished during the Triassic. The most basal (earliest-branching) and plesiomorphic ("primitive") known avemetatarsalians were the aphanosaurs. Aphanosaurs were rare, four-legged carnivores which were only properly distinguished as a group in 2017.[5] The split between dinosaurs and pterosaurs occurred just after aphanosaurs branched off the archosaur family tree. This split corresponds to the subgroup Ornithodira (Ancient Greek ὄρνις (órnis, “bird”) + δειρή (deirḗ, “throat”), defined as the last common ancestor of dinosaurs and pterosaurs, and all of its descendants. Until the discovery of aphanosaurs, Ornithodira and Avemetatarsalia were considered roughly equivalent concepts.[3]

Pterosauromorpha includes all avemetatarsalians closer to pterosaurs than to dinosaurs. True non-pterosaur pterosauromorphs have been historically difficult to determine. Small, insectivorous archosaurs of the family Lagerpetidae may potentially be examples, alongside the similar genus Scleromochlus.[6] Dinosauromorpha, on the other hand, includes all avemetatarsalians closer to dinosaurs than to pterosaurs. Probable non-dinosaur dinosauromorphs include the diverse and widespread silesaurids, as well as more controversial and fragmentary taxa such as Marasuchus, Lagosuchus, Nyasasaurus, and Saltopus. Lagerpetids were also traditionally considered dinosauromorphs,[7][3] though this has been more recently debated.[8][6][9]

  1. ^ Brusatte, S. L.; Niedźwiedzki, G.; Butler, R. J. (2011). "Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic". Proceedings of the Royal Society B: Biological Sciences. 278 (1708): 1107–1113. doi:10.1098/rspb.2010.1746. PMC 3049033. PMID 20926435.
  2. ^ a b Benton, M.J. (1999). "Scleromochlus taylori and the origin of dinosaurs and pterosaurs". Philosophical Transactions of the Royal Society B: Biological Sciences. 354 (1388): 1423–1446. doi:10.1098/rstb.1999.0489. PMC 1692658.
  3. ^ a b c Nesbitt, S.J. (2011). "The early evolution of archosaurs: relationships and the origin of major clades". Bulletin of the American Museum of Natural History. 352: 1–292. doi:10.1206/352.1. hdl:2246/6112. S2CID 83493714.
  4. ^ Ezcurra, Martín D.; Nesbitt, Sterling J.; Bronzati, Mario; Dalla Vecchia, Fabio Marco; Agnolin, Federico L.; Benson, Roger B. J.; Brissón Egli, Federico; Cabreira, Sergio F.; Evers, Serjoscha W.; Gentil, Adriel R.; Irmis, Randall B.; Martinelli, Agustín G.; Novas, Fernando E.; Roberto da Silva, Lúcio; Smith, Nathan D.; Stocker, Michelle R.; Turner, Alan H.; Langer, Max C. (2020). "Enigmatic dinosaur precursors bridge the gap to the origin of Pterosauria". Nature. 588 (7838): 445–449. doi:10.1038/s41586-020-3011-4. ISSN 1476-4687. PMID 33299179. S2CID 228077525.
  5. ^ Nesbitt, Sterling J.; Butler, Richard J.; Ezcurra, Martín D.; Barrett, Paul M.; Stocker, Michelle R.; Angielczyk, Kenneth D.; Smith, Roger M. H.; Sidor, Christian A.; Niedźwiedzki, Grzegorz; Sennikov, Andrey G.; Charig, Alan J. (2017). "The earliest bird-line archosaurs and the assembly of the dinosaur body plan" (PDF). Nature. 544 (7651): 484–487. Bibcode:2017Natur.544..484N. doi:10.1038/nature22037. PMID 28405026. S2CID 9095072.
  6. ^ a b Cite error: The named reference :1 was invoked but never defined (see the help page).
  7. ^ Gauthier, Jacques (1986). "Saurischian monophyly and the origin of birds". In Padian, Kevin (ed.). The Origin of Birds and the Evolution of Flight. Memoirs of the California Academy of Sciences. Vol. 8. San Francisco: California Academy of Sciences. pp. 1–55.
  8. ^ Cite error: The named reference :2 was invoked but never defined (see the help page).
  9. ^ Baron, Matthew G. (2021-08-20). "The origin of Pterosaurs". Earth-Science Reviews. 221: 103777. doi:10.1016/j.earscirev.2021.103777. ISSN 0012-8252.