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Clade
Subclade

Taxon
Taxon
Styracosterna
Nominal Author
Sereno 1986
2nd Nominal Author
Taxon Status ACTIVE
Comments
The definition is a first-order revision of the initial and, to date, only prior definition (Sereno 1998). This stem-based definition is party to a node-stem triplet that has been stable in phylogenetic analyses of ornithopods. Norman (2004:434) provided a partial node-based definition that cites only one internal specifier: “Lurdusaurus and all more derived iguanodontians.” He did not cite Sereno’s prior stem-based definition nor give any reason for suggesting its conversion to a node-based definition. Norman disagreed with the position of Probactrosaurus gobiensis at the base of Styracosterna (Sereno 1986, 1999). This is irrelevant to the definition of Styracosterna (Sereno 1998), which is framed in reference to Camptosaurus as an external specifier.
Potential Synonomy
Iguanodontoidea

Active Phylogenetic Definition
Active Definition
The most inclusive clade containing Parasaurolophus walkeri Parks 1922 but not Camptosaurus dispar (Marsh 1879).
Shorthand
> Parasaurolophus walkeri but not Camptosaurus dispar.
Definitional Author
Sereno 2005
Definition Status checked
Definition Type STEM
Node-Stem Triplet STEM
Other Triplet Taxa
Ankylopollexia, Camptosauridae
Specifiers
Specifier(s) A
Parasaurolophus walkeri
Specifier(s) B
Specifier(s) C
Camptosaurus dispar
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown
1998

Inactive Taxon Status
Rejection Criteria
Critique
 

Definitional History #1
Earliest Record
All ankylopollexians closer to Parasaurolophus than to Camptosaurus.
Latest Record
Sereno 1998:62
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Camptosaurus, Parasaurolophus
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