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Clade
Subclade

Taxon
Taxon
Euornithopoda
Nominal Author
Sereno 1986
2nd Nominal Author
Taxon Status ACTIVE
Comments

The active definition is a first-order revision of the original and only previous definition (Sereno 1998) that includes additional external specifiers to ensure stability of taxonomic content under alternative hypotheses of the higher-level phylogeny of Ornithischia.

Recently Butler (2005) proposed an alternative cladogram disbanding taxa central to this clade. His strict consensus tree (Butler 2005:fig. 25) does not show any special relationship between taxa regarded as hypsilophodontids and Iguanodontia. This unusual result, which differs from Sereno (1986, 1999) and all previous quantitative analyses, would appropriately eliminate use of the taxon Euornithopoda, as here defined and as used in the literature since the mid 1980’s. Butler’s result, however, is unconventional and may well not survive future cladistic tests. The point here, nonetheless, is that the active definition restricts use of Euornithopoda to clades that maintain taxonomic content similar to its previous usage in the literature.

Potential Synonomy

Active Phylogenetic Definition
Active Definition
The most inclusive clade containing Parasaurolophus walkeri Parks 1922 but not Heterodontosaurus tucki Crompton and Charig 1962, Pachycephalosaurus wyomingensis (Gilmore 1931), Triceratops horridus Marsh 1889, Ankylosaurus magniventris Brown 1908.
Shorthand
> Parasaurolophus walkeri but not Heterodontosaurus tucki, Pachycephalosaurus wyomingensis, Triceratops horridus, Ankylosaurus magniventris.
Definitional Author
Sereno 2005
Definition Status checked
Definition Type STEM
Node-Stem Triplet STEM
Other Triplet Taxa
Ornithopoda, Heterodontosauridae
Specifiers
Specifier(s) A
Parasaurolophus walkeri
Specifier(s) B
Specifier(s) C
Heterodontosaurus tucki, Pachycephalosaurus wyomingensis, Triceratops horridus, Ankylosaurus magni
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown
1998

Inactive Taxon Status
Rejection Criteria
Critique
 

Definitional History #1
Earliest Record
All ornithopods closer to Parasaurolophus than to Heterodontosaurus.
Latest Record
Sereno 1998:61
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Parasaurolophus, Heterodontosaurus
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