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Clade
Subclade

Taxon
Taxon
Therizinosauridae
Nominal Author
Maleev 1954
2nd Nominal Author
Taxon Status ACTIVE
Comments

Sereno (1998) proposed a stem-based definition for this clade including all ornithomimosaurs closer to Erlikosaurus than to Ornithomimus. Its position within Ornithomimosauria, however, is tentative and controversial. For this reason, Sereno (1999b) added additonal external specifiers such as Oviraptor and Neornithes. Zhang et al. (2001) departed from this model, using Therizinosauroidea in a similar manner for the group as a whole, which is probably the most common taxon used for this purpose. They proposed a more restricted node-based definition for Therizinosauridae, identifying a subgroup of therizinosauroids. More recently, Clark et al. (2004) criticized Sereno’s (1998) definition for not including Therizinosaurus as a specifier for its nominal family-level taxon, apparently unaware of the revised definition in Zhang et al. (2001). Zanno (2004:134A) proposed a partial definition in the same spirit (although not clearly stated as node- or stem-based).

The active definition is a first-order revision of the definition in Zhang et al. (2001). It uses Therizinosaurus cheloniformis as the mandatory internal specifier and cites two well known basal forms from the early Late Cretaceous as internal specifiers (Neimongosaurus yangi, Nothronychus mckinleyi).

Potential Synonomy
Therizinosauroidea

Active Phylogenetic Definition
Active Definition
The least inclusive clade containing Therizinosaurus cheloniformis Maleev 1954, Neimongosaurus yangi Zhang et al. 2001, Nothronychus mckinleyi Kirkland and Wolfe 2001.
Shorthand
< Therizinosaurus cheloniformis and Neimongosaurus yangi, Nothronychus mckinleyi.
Definitional Author
Sereno 2005
Definition Status checked
Definition Type NODE
Node-Stem Triplet NO
Other Triplet Taxa
Specifiers
Specifier(s) A
Therizinosaurus cheloniformis
Specifier(s) B
Segnosaurus galbinensis, Erlikosaurus andrewsi, Nanshiungosaurus brevispinus
Specifier(s) C
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown
2001

Inactive Taxon Status
Rejection Criteria
Critique
 

Definitional History #1
Earliest Record
All ornithomimosaurs closer to Erlikosaurus than to Ornithomimus.
Latest Record
Sereno 1998:65
Range (My)
Range (My)
Erlikosaurus, Ornithomimus
Range (My)

Definitional History #2
Earliest Record
All maniraptoriformes closer to Erlikosaurus than to Ornithomimus, Oviraptor, or Neornithes.
Latest Record
Sereno 1999b:2147
Range (My)
Range (My)
Erlikosaurus, Ornithomimus, Oviraptor, Neornithes
Range (My)

Definitional History #3
Earliest Record
Segnosaurus, Erlikosaurus, Nanshiungosaurus, Therizinosaurus, their common ancestor and all descendants.
Latest Record
Zhang et al. 2001:39
Range (My)
Range (My)
Segnosaurus, Erlikosaurus, Nanshiungosaurus, Therizinosaurus
Range (My)

Definitional History #4
Earliest Record
The least inclusive clade including Therizinosaurus and Erlikosaurus.
Latest Record
Clark et al. 2004:162
Range (My)
Range (My)
Therizinosaurus, Erlikosaurus
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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