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Clade
Subclade

Taxon
Taxon
Arctometatarsalia
Nominal Author
Holtz 1994
2nd Nominal Author
Taxon Status INACTIVE
Comments
Potential Synonomy
Ornithomimiformes, Ornithomimosauria

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

This taxon is considered inactive, because there is little support for the taxon under its original apomorphy-based definition. Arctometatarsalia was coined as the flagship taxon to reorganize theropod phylogeny (Holtz 1994). Holtz coined and defined Arctometatarsalia as the first theropod with the arctometatarsalian condition and all of its descendants, an incomplete definition (as there is no specific internal specifier mentioned). He intended the clade to include Ornithomimosauria, Tyrannosauridae, Troodontidae, Elmisauridae and Avimimus but to exclude Dromaeosauridae and birds.

Later Holtz (1996) replaced this form-qualified definition with a simple stem-based definition: the clade composed of Ornithomimus and all theropods sharing a more recent common ancestor with Ornithomimus than with birds. Subsequently Holtz (2000) replaced the vulgar term “birds” with Neornithes.

The new taxonimic content of the taxon, however, no longer resembles the original, which was the signpost for a radically different phylogenetic hypothesis within Coelurosauria (see Ornithomimosauria). Because other taxa are available that do not have this history, Arctometatarrsalia is here regarded as inactive.

 

Definitional History #1
Earliest Record
The first theropod to develop the arctometatarsalian pes and all of its descendants.
Latest Record
Holtz 1994:1108
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(none)
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Definitional History #2
Earliest Record
Ornithomimus and all theropods sharing a more recent common ancestor with Ornithomimus than with birds.
Latest Record
Holtz 1996:536
Range (My)
Range (My)
Ornithomimus, birds
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Definitional History #3
Earliest Record
Ornithomimus and all taxa sharing a more recent common ancestor with Ornithomimus than with Neornithes.
Latest Record
Holtz 2000:28
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Range (My)
Ornithomimus, Neornithes
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Definitional History #4
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Definitional History #5
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Definitional History #6
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Definitional History #7
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Definitional History #8
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Definitional History #9
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Definitional History #10
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