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Clade
Subclade

Taxon
Taxon
Aves
Nominal Author
Linnaeus 1758
2nd Nominal Author
Taxon Status ACTIVE
Comments
The eight distinct phylogenetic definitions that have been generated for the taxon Aves can be subdivided into two basic approaches: (1) restricting Aves to crown-clade birds (as a replacement for Neornithes) or (2) maintaining more inclusive taxonomic content anchored on the extinct taxon Archaeopteryx lithographica. The second approach recognizes what might be termed a “traditional” Aves and is preferred here because justification for globally repositioning commonly-used taxa is regarded as flawed (Sereno 1998, 2005). The dual use of Aves is likely to persist for some time. A crown clade definition for Aves was first proposed by Gauthier (1986) and later revised by Gauthier & de Queiroz (2001). Arguing that this is a better match to the original use of the name by Linnaeus, they set aside the last 150 years of modern taxonomy during which Aves was applied to living birds plus their fossil antecedents. Gauthier (1986) replaced this traditional concept of Aves with Avialae, although the phylogenetic definitions of these two taxa differ—one node-based and the other stem-based. They are not synonyms. Gauthier (1986:36) explicitly defined Avialae as a stem-based taxon including all taxa closer to birds than to Deinonychosauria. Subsequently, Gauthier and de Queiroz (2001:25-26) claimed that Gauthier (1986) really did not define Avialae. They proposed a form-qualified (“apomorphy-based”) definition based on the presence of “feathered wings . . . used for powered flight,” a definition that ranks among the most ambiguous (Sereno 2005). Gauthier (1986:36), nevertheless, was very explicit in formulating a stem-based definition for this taxon. More recently, Clarke (2004) unwittingly proposed a new node-based definition for Avialae, attributing it in error to Gauthier (1986). Ironically, Clarke’s new definition now identifies the same node-based clade that many of us would like to continue to reserve for Aves. This second option follows another tradition dating back 150 years to the discovery of the basal bird Archaeopteryx lithographica. Three similar node-based definitions were proposed independently in the same year by Sereno (1997, 1998), Chiappe (1997) and Padian (1997). All used Archaeopteryx to anchor the definition but sampled more derived birds in different ways (Passeriformes, extinct birds, extant birds). The active definition is a first-order revision that uses Archaeopteryx lithographica and Passer domesticus as specifiers.
Potential Synonomy

Active Phylogenetic Definition
Active Definition
The least inclusive clade containing Archaeopteryx lithographica Meyer 1861 and Passer domesticus (Linnaeus 1758).
Shorthand
< Archaeopteryx lithographica and Passer domesticus.
Definitional Author
Sereno 2005
Definition Status checked
Definition Type NODE
Node-Stem Triplet NODE
Other Triplet Taxa
Ornithurae, Archaeopterygidae
Specifiers
Specifier(s) A
Archaeopteryx lithographica
Specifier(s) B
Passer domesticus
Specifier(s) C
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown
1997

Inactive Taxon Status
Rejection Criteria
Critique
 

Definitional History #1
Earliest Record
All descendants of the most recent common ancestor of Ratiti, Tinami, and Neognathae.
Latest Record
Gauthier 1986:14
Range (My)
Range (My)
Ratitiae, Tinamidae, Neognathae
Range (My)

Definitional History #2
Earliest Record
Archaeopteryx, Passeriformes, and their common ancestor and all descendants.
Latest Record
Sereno 1997:459
Range (My)
Range (My)
Archaeopteryx, Passeriformes
Range (My)

Definitional History #3
Earliest Record
Archaeopteryx plus extinct birds and all descendants of their most recent common ancestor.
Latest Record
Chiappe 1997:32
Range (My)
Range (My)
Archaeopteryx, extinct birds
Range (My)

Definitional History #4
Earliest Record
Archaeopteryx, extant birds, and all descendants of their most recent common ancestor.
Latest Record
Padian 1997:39
Range (My)
Range (My)
Archaeopteryx, extant birds
Range (My)

Definitional History #5
Earliest Record
Archaeopteryx, Neornithes, their most recent common ancestor and all descendants.
Latest Record
Sereno 1998:65
Range (My)
Range (My)
Archaeopteryx, Neornithes
Range (My)

Definitional History #6
Earliest Record
The crown clade stemming from the most recent common ancestor of Ratitae (Struthio camelus Linnaeus 1758), Tinamidae (Tetrao [Tinamus] major Gmelin 1789), and Neognathae (Vultur gryphus Linnaeus 1758).
Latest Record
Gauthier and de Queiroz 2001:29
Range (My)
Range (My)
Struthio camelus, Tetrao [Tinamus] major,Vultur gryphus
Range (My)

Definitional History #7
Earliest Record
All taxa phylogenetically bracketed by Archaeopteryx and Ornithurae.
Latest Record
Senter et al. 2004:19
Range (My)
Range (My)
Archaeopteryx, Ornithurae
Range (My)

Definitional History #8
Earliest Record
The last common ancestor of all living birds and all of its descendants.
Latest Record
Clarke 2004:18
Range (My)
Range (My)
all living birds
Range (My)

Definitional History #9
Earliest Record
Latest Record
Range (My)
Range (My)
Range (My)

Definitional History #10
Earliest Record
Latest Record
Range (My)
Range (My)
Range (My)