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Clade
Subclade

Taxon
Taxon
Troodontidae
Nominal Author
Gilmore 1924b
2nd Nominal Author
Taxon Status ACTIVE
Comments

The original stem-based definition by Varricchio (1997) lists several internal specifiers, some of which are poorly known (e.g. Borogovia) and several external specifiers including “other well defined taxa”. In recent quantitative analyses, the only coelurosaurs that have been placed as sister taxon to troodontids besides dromaeosaurids are ornithomimosaurs and birds.

Thus the active definition is a first-order revision that uses species as specifiers and includes nested species from plausible sister taxa as external specifiers.

Potential Synonomy

Active Phylogenetic Definition
Active Definition
The most inclusive clade containing Troodon formosus Leidy 1856 but not Velociraptor mongoliensis Osborn 1924, Ornithomimus edmontonicus Sternberg 1933, Passer domesticus (Linnaeus 1758).
Shorthand
> Troodon formosus but not Velociraptor mongoliensis, Ornithomimus edmontonicus, Passer domesticus.
Definitional Author
Sereno 2005
Definition Status checked
Definition Type STEM
Node-Stem Triplet STEM
Other Triplet Taxa
Deinonychosauria, Dromaeosauridae
Specifiers
Specifier(s) A
Troodon formosus
Specifier(s) B
Specifier(s) C
Velociraptor mongoliensis, Ornithomimus edmontonicus, Passer domesticus
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown
1997

Inactive Taxon Status
Rejection Criteria
Critique
 

Definitional History #1
Earliest Record
Troodon, Sinornithoides, Saurornithoides, Borogovia, and all coelurosaurs closer to them than to ornithomimids, oviraptorosaurs, or other well-defined taxa.
Latest Record
Varricchio 1997:
Range (My)
Range (My)
Troodon, Sinornithoides, Saurornithoides, Borogovia, ornithomimids, oviraptorosaurs, and “other well-defined taxa”.
Range (My)

Definitional History #2
Earliest Record
All deinonychosaurs closer to Troodon than to Velociraptor.
Latest Record
Sereno 1998:65
Range (My)
Range (My)
Troodon, Velociraptor
Range (My)

Definitional History #3
Earliest Record
All taxa more closely related to Troodon than to Ornithomimus, Mononykus, Therizinosaurus, Velociraptor, Oviraptor, or Aves.
Latest Record
Senter et al. 2004:18
Range (My)
Range (My)
Troodon, Ornithomimus, Mononykus, Therizinosaurus, Velociraptor, Oviraptor, Aves.
Range (My)

Definitional History #4
Earliest Record
All taxa that are closer to Troodon formosus than to Velociraptor mongoliensis.
Latest Record
Makovicky and Norell 2004:184
Range (My)
Range (My)
Troodon formosus, Velociraptor mongoliensis
Range (My)

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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