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Clade
Subclade

Taxon
Taxon
Titanosauria
Nominal Author
Bonaparte and Coria 1993
2nd Nominal Author
Taxon Status ACTIVE
Comments

Titanosauria has been defined both as a node- and stem-based taxon. The active definition is stem-based, although this was not the form of the first definition.

Bonaparte and Coria (1993) coined Titanosauria but did not provide a definition. The first definition, a node-based definition based on Andesaurus delgadoi, was provided by Salgado et al. (1997). Wilson and Upchurch (2003:154) recently advocated use of the node-based definition of Salgado et al. (1997) for two reasons, namely it (1) captured the intent of Bonaparte and Coria (1993) and (2) has priority. Bonaparte and Coria (1993), however, only listed included taxa. They did not specify a definition, and thus there is no way to know whether they would have included newfound basalmost taxa. There is no issue with the second point. Salgado et al. (1997) were first to erect a definition, which like all others in their paper was node-based. But is a node-based definition the most effective for a clade with an increasing number of basal singleton taxa, some of which are based on very incomplete type speccimens?

Sereno (1998) and Wilson and Sereno (1998) proposed a stem-based defintion because the type material of Andesaurus delgadoi is poorly known other taxa considered basal titanosaurians (e.g. Chubutisaurus, Salgado et al. 1997) may eventually reside in a more basal position. Recently Salgado (2003) has also adopted a stem-based definition for Titanosauria proposed by Sereno (1998) and Wilson and Sereno (1998).

Thus the active definition is a first-order revision of that in Wilson and Sereno (1998) that includes two additional external specifiers (Euhelopus zdanskyi, Brachiosaurus brancai) for stability of taxonomic content in the face of potential phylogenetic change among immediate outgroups.

Potential Synonomy

Active Phylogenetic Definition
Active Definition
The most inclusive clade containing Saltasaurus loricatus Bonaparte and Powell 1980 but not Euhelopus zdanskyi (Wiman 1929), Brachiosaurus brancai Janensch 1914.
Shorthand
> Saltasaurus loricatus but not Euhelopus zdanskyi, Brachiosaurus brancai.
Definitional Author
Sereno 2005
Definition Status checked
Definition Type STEM
Node-Stem Triplet NO
Other Triplet Taxa
Specifiers
Specifier(s) A
Saltasaurus loricatus
Specifier(s) B
Specifier(s) C
Euhelopus zdanskyi, Brachiosaurus brancai
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown
1998

Inactive Taxon Status
Rejection Criteria
Critique
 

Definitional History #1
Earliest Record
The most recent common ancestor of Andesaurus delgadoi and Titanosauridae and all of its descendants.
Latest Record
Salgado et al. 1997:18
Range (My)
Range (My)
Saltasaurus, Euhelopus
Range (My)

Definitional History #2
Earliest Record
Titanosauriforms more closely related to Saltasaurus than to either Brachiosaurus or Euhelopus.
Latest Record
Wilson and Sereno 1998:22
Range (My)
Range (My)
Saltasaurus, Brachiosaurus, Euhelopus
Range (My)

Definitional History #3
Earliest Record
All somphospondyls closer to Saltasaurus than to Euhelopus.
Latest Record
Sereno 1998:63
Range (My)
Range (My)
Saltasaurus, Euhelopus
Range (My)

Definitional History #4
Earliest Record
Andesaurus delgadoi, Saltasaurus loricatus, their most recent common ancestor and all descendants.
Latest Record
Wilson and Upchurch 2003:156
Range (My)
Range (My)
Andesaurus delgadoi, Saltasaurus loricatus
Range (My)

Definitional History #5
Earliest Record
Titanosauriformes more closely related to Saltasaurus than to Brachiosaurus.
Latest Record
Upchurch et al. 2004:309
Range (My)
Range (My)
Saltasaurus, Brachiosaurus
Range (My)

Definitional History #6
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Definitional History #7
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Definitional History #8
Earliest Record
Latest Record
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Definitional History #9
Earliest Record
Latest Record
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Definitional History #10
Earliest Record
Latest Record
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