Zanabazar junior

Zanabazar is an extinct genus of troodontid theropod dinosaur from the Late Cretaceous of Mongolia. The genus was originally named by Rinchen Barsbold as a species of Saurornithoides, S. junior. In 2009 it was reclassified as its own genus, named after the first spiritual figurehead of Tibetan buddhism, Zanabazar. The holotype, GIN 100–1, includes a skull, vertebrae, and right hindlimb. Zanabazar was one of the largest and most derived troodontids.

Zanabazar junior
Temporal range: Late Cretaceous, 70 Ma
↓
Skeletal restoration by Jaime Headden
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Troodontidae
Genus: †Zanabazar
Norell et al., 2009
Species:
†Z. junior
Binomial name
†Zanabazar junior
Synonyms

History of discovery

In 1974, Rinchen Barsbold described a new specimen of derived theropod from the Bugeen Tsav of the Nemegt Formation, which is dated to about 70 million years ago.[1][2] This specimen, GI No. SPS 100–1, was named by Barsbold as a new species of Saurornithoides, S. junior. The skeleton includes a nearly complete skull and braincase, part of the pelvis, some tail vertebrae, and parts of the right hindlimb.[1] In 2009 a review of the genus found that the support for S. junior in the same genus as S. mongoliensis was lacking. Mark Norell and colleagues re-classified the species in the new genus Zanabazar, which they named in honor of Zanabazar, the first spiritual head (Bogd Gegen) of Tibetan Buddhism in Outer Mongolia.[2]

Description
Reconstructed skull by Jaime Headden

Zanabazar is the largest known Asian troodontid, with a skull length of 272 millimetres (10.7 in). At the time of its discovery, the only other troodontids that appeared to be larger than it were specimens from Alaska currently classified in the genus Troodon.[2] Latenivenatrix mcmasterae is now considered the largest troodontid.[3]


Classification

While originally included in Saurornithoides, within the family Saurornithoididae, Zanabazar is now thought to be a derived member of Troodontidae.[1][2]

Life restoration of Zanabazar junior
Comparison of troodontid teeth; C, D, F, and G are Zanabazar

The cladogram below shows the phylogenetic position of Zanabazar among other troodontids following a 2014 analysis.[4]

Paraves 
 

Avialae

 
 Deinonychosauria 
 

Dromaeosauridae

 
 Troodontidae 
 

Sinovenator

 
 
 

Anchiornis

 
 
 

Mei

 
 

Talos

 
 
 

Byronosaurus

 
 
 

IGM 100/44

 
 

Sinornithoides

 
 
 
 

Linhevenator

 
 

Philovenator

 
 
 
 

Gobivenator

 
 
 

Troodon

 
 
 

Saurornithoides

 
 

Zanabazar

 
 
 
 
 
 
 
 
 
 
 
 

See also

References
  1. Barsbold, R. (1974). "Saurornithoididae, a new family of small theropod dinosaurs from Central Asia and North America" (PDF). Palaeontologica Polonica. 30: 5–22.
  2. Norell, M.A.; Makovicky, P.J.; Bever, G.S.; Balanoff, A.M.; Clark, J.M.; Barsbold, R.; Rowe, T. (2009). "A Review of the Mongolian Cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda)". American Museum Novitates. 3654: 63. doi:10.1206/648.1. hdl:2246/5973.
  3. van der Reest, Aaron J.; Currie, Philip J. (2017-08-08). "Troodontids (Theropoda) from the Dinosaur Park Formation, Alberta, with a description of a unique new taxon: implications for deinonychosaur diversity in North America". Canadian Journal of Earth Sciences. 54 (9): 919–935. doi:10.1139/cjes-2017-0031. hdl:1807/78296. ISSN 0008-4077.
  4. Tsuihiji, T.; Barsbold, R.; Watabe, M.; Tsogtbaatar, K.; Chinzorig, T.; Fujiyama, Y.; Suzuki, S. (2014). "An exquisitely preserved troodontid theropod with new information on the palatal structure from the Upper Cretaceous of Mongolia". Naturwissenschaften. 101 (2): 131–142. doi:10.1007/s00114-014-1143-9. PMID 24441791.


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