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Avemetatarsalia
Fossil range: Middle Triassic - Recent
Panaves diversity
Clockwise from top-left: Tupuxuara leonardi (a pterosaur), Alamosaurus sanjuanensis, (a sauropod), Tsintaosaurus spinorhinus (an ornithopod), Daspletosaurus torosus (a tyrannosaur), Pentaceratops sternbergii (a ceratopsian), and Grus grus (a neornithian).
Scientific classification

Subclass:

Diapsida

Infraorder:

Archosauromorpha

(Unranked) :

Archosauria

(Unranked) :

Avemetatarsalia
Benton, 1999

Subdivisions:

Avemetatarsalia (meaning "bird metatarsals") is a clade name established by British palaeontologist Michael Benton in 1999 for all avesuchians (crown group archosaurs) that are closer to dinosaurs than to crocodiles.[1]

An improved description of the small archosaur Scleromochlus together with a cladistic analysis of its phylogenetic position demonstrated that Scleromochlus was more closely related to the dinosaurs than to the Crurotarsi (to which the crocodiles belong) but outside of the node-based clade Ornithodira as originally interpreted by Jacques Gauthier: the group containing the last common ancestor of the dinosaurs and the pterosaurs and all of its descendants.[1]

Paul Sereno had in 1991 given a formal (and different) definition of Ornithodira, one in which Scleromochlus was explicitly added.[2] However, at that point, there was no named clade that could encompass species with a basal position on the archosaurian branch leading to dinosaurs (as opposed to that leading to crocodiles) so Benton named a new branch-based clade for this purpose: Avemetatarsalia, named after the birds (Aves), the last surviving members of the clade, and the metatarsal ankle joint that was a typical character of the group. Avemetatarsalia was defined as: all Avesuchia closer to Dinosauria than to Crocodylia.


ReferencesEdit

  1. ^ a b Benton, M.J. (1999). Scleromochlus taylori and the origin of dinosaurs and pterosaurs. Philosophical Transactions of the Royal Society of London 354:1423-1446.
  2. ^ Sereno, P. C. 1991. Basal archosaurs: phylogenetic relationships and functional implications. Journal of Vertebrate Paleontology Memoir 2, 11(4, Supplement):1-53.

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