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Clade
Subclade

Taxon
Taxon
Diplodocimorpha
Nominal Author
Calvo and Salgado 1995
2nd Nominal Author
Taxon Status INACTIVE
Comments
Potential Synonomy
Diplodocoidea

Active Phylogenetic Definition
Active Definition
Shorthand
Definitional Author
Definition Status Unknown
Definition Type Unknown
Node-Stem Triplet Unknown
Other Triplet Taxa
Specifiers
Specifier(s) A
Specifier(s) B
Specifier(s) C
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown

Inactive Taxon Status
Rejection Criteria other
Critique
The name was coined (Calvo and Salgado 1995) to include Rebbachisaurus tessonei and Diplodocidae. This species was later referred to Rayosaurus (Bonaparte 1996) and then to a new genus Limaysaurus (Salgado et al. 2004).

The taxon has not been widely used since then. Rather Diplodocoidea, coined by Upchurch (1995) and defined by Sereno (1998) and Wilson and Sereno (1998), has been the taxon of choice. They are not the same taxon, as Diplodocoidea is stem-based and Diplodocimorpha node-based. Nevertheless, they currently have identical taxonomic content and in that sense are redundant. As there is little reason to have two taxa with the same taxonomic content, Diplodocimorpha is regarded as inactive for the itme being.

Recently Taylor and Naisch (2005:3, 4) recounted this taxonomic history, stating that Wilson and Sereno (1998) regarded Diplodocimorpha and Diplodocoidea as “equivalent.” Wilson and Sereno (1998:6), however, did not describe the comparison in that manner, observing only that Diplodocoidea has long been available as a family-group name and seemed appropriate for the observed diversity. By resurrecting Diplodocimorpha as a node-based group, Taylor and Naisch (2005) correctly observed that it is inserted within more than a half dozen consistent family-group names (Dipldocoidea, Rebbachisauridae, Diplodocidae, Apatosauridae, etc.). There seems little justification for this, and it has the potential to mislead those who are not familiar with the taxonomy of the group. In this compilation, the relative inclusiveness of taxa with Linnean family-group suffixes is respected for historical and newly coined taxa. This is a longstanding taxonomic pattern that is easy to accommodate in a phylogenetic taxonomy. Setting aside this pattern is difficult to regard as a “best practice in the use of names” (Taylor and Naisch 2005:4).

In addition, there is some confusion in ther presentation of a revised definition for Diplodocimorpha. Their intent was to provide a first-order revision of the original node-based definition of Calvo and Salgado (1995). In a table, they list “(Diplodocus + Rebbachisaurus)” and in the text indicate that this is shorthand for “the least inclusive clade containing . . .” (Taylor and Naisch 2005:1, table 1). In a footnote, however, they stated that their definition “uses the type species of Rebbbachisaurus, R. garasbae”. Yet it clearly refers only to the genus. This is not a trivial difference, especially as more than one species has been assigned to Rebbachisaurus.
 

Definitional History #1
Earliest Record
Rebbachisaurus tessonei sp. nov., Diplodocidae, and all descendants of their common ancestor.
Latest Record
Calvo and Salgado 1995:14
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Rebbachisaurus tessonei, Diplodocidae
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Definitional History #2
Earliest Record
(Diplodocus + Rebbachisaurus)
Latest Record
Taylor and Naisch 2005:5
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Diplodocus, Rebbachisaurus
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