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Clade
Subclade

Taxon
Taxon
Dinosauria
Nominal Author
Owen 1842
2nd Nominal Author
Taxon Status ACTIVE
Comments

For most of this century, dinosaurs have been divided into Ornithischia and Saurischia either as independent groups or as subdivisions of Dinosauria. Dinosaurian monophyly was reestablished in the cladistic era with birds as descendants. The first definition for Dinosauria was proposed by Novas (1992:60) as “The common ancestor of Herrerasauridae plus Saurischia + Ornithischia, and all of its descendants.” Saurischia and Ornithischia were joined as Eudinosauria, a taxon that never gained currency.

Padian & May (1993:379) proposed a second-order revision, intentionally assigning Dinosauria to a less inclusive clade as “All descendants of the most recent common ancestor of birds and Triceratops.” This clade, equivalent to Novas’ Eudinosauria, is specified in all subsequent definitional variations for Dinosauria (Sereno 1998, Olshevsky 2000, Fraser et al. 2002). The active definition, a first-order revision of that given by Padian & May (1993), uses Triceratops horridus and Passer domesticus as specifiers.

It makes little sense to use the oldest genera or species as specifiers just because they were originally included by the nominal author of a taxon. Clarke (2004), for example, used the poorly understood genus Megalosaurus as a specifier for Dinosauria. Historic nominal authors often included taxa later found to have disparate relationships (e.g. Cope’s original Archosauria). The prevailing taxonomic content of a taxon over time is what constitutes prior use and is most important to recognize. Using Passer domesticus as a specifier for Dinosauria does mandate the inclusion of birds, something that Owen would not have been anticipated. Taxonomy, nonetheless, need not be shackled by the work of nineteenth century taxonomists, whose access to paleontologic and comparative information was far more limited.

Potential Synonomy
Eudinosauria, Deinosauria (Watson 1957, spelling variant), Dinosauri (Bronn 1851-1852, spelling variant)

Active Phylogenetic Definition
Active Definition
The least inclusive clade containing Triceratops horridus Marsh 1889 and Passer domesticus (Linnaeus 1758).
Shorthand
< Triceratops horridus and Passer domesticus.
Definitional Author
Sereno 2005
Definition Status checked
Definition Type NODE
Node-Stem Triplet NODE
Other Triplet Taxa
Ornithischia, Saurischia
Specifiers
Specifier(s) A
Triceratops horridus
Specifier(s) B
Passer domesticus
Specifier(s) C
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown
1992

Inactive Taxon Status
Rejection Criteria
Critique
 

Definitional History #1
Earliest Record
The common ancestor of Herrerasauridae plus Saurischia + Ornithischia, and all of its descendants.
Latest Record
Novas 1992a:60
Range (My)
Range (My)
Herrerasauridae, Saurischia, Ornithischia
Range (My)

Definitional History #2
Earliest Record
All descendants of the most recent common ancestor of birds and Triceratops.
Latest Record
Padian and May 1993:379
Range (My)
Range (My)
birds, Triceratops
Range (My)

Definitional History #3
Earliest Record
Triceratops, Neornithes, their most recent common ancestor and all descendants.
Latest Record
Sereno 1998:61
Range (My)
Range (My)
Triceratops, Neornithes
Range (My)

Definitional History #4
Earliest Record
Most recent common ancestor of Megalosaurus and Iguanodon and all its descendants.
Latest Record
Olshevsky 2000:3
Range (My)
Range (My)
Megalosaurus, Iguanodon
Range (My)

Definitional History #5
Earliest Record
Triceratops (representing Ornithischia) plus Aves (representing Saurischia) and all descendants of their last common ancesor.
Latest Record
Fraser et al. 2002:86
Range (My)
Range (My)
Triceratops, Aves
Range (My)

Definitional History #6
Earliest Record
Latest Record
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Range (My)
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Definitional History #7
Earliest Record
Latest Record
Range (My)
Range (My)
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Definitional History #8
Earliest Record
Latest Record
Range (My)
Range (My)
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Definitional History #9
Earliest Record
Latest Record
Range (My)
Range (My)
Range (My)

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