Zanabazar junior

Zanabazar (meaning "Zanabazar") is a genusof large troodontid dinosaurs from the Late Cretaceous of Mongolia. The genus was originally named by Rinchen Barsbold as the new species Saurornithoides junior. In 2009 it was reclassified as its own genus and species, Zanabazar junior, named after the first spiritual figurehead of Tibetan buddhism, Zanabazar. The holotype includes a skull, vertebrae, and right hindlimb. Zanabazar was one of the largest and most derivedtroodontids.

Zanabazar junior
Temporal range: Late Cretaceous,
~70 Ma 
PreꞒ
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O
S
D
C
P
T
J
K
Pg
N
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Skull
Skeletal restoration of IGM 100/1
Scientific classificationedit
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
(Barsbold, 1974)
Synonyms
  • Saurornithoides junior Barsbold, 1974

History of discoveryEdit

Reconstructed skull of IGM 100/1

The holotype was discovered in 1964 from the Bügiin Tsav locality of the Nemegt Formationand initially described by Rinchen Barsbold as a new species of Saurornithoides (S. junior) in 1974. This specimen, IGM 100/1, 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]

DescriptionEdit

Size comparison of the holotype

Zanabazar were large troodontids reaching 2.3 m (7.5 ft) in length and weighing 25 kg (55 lb).[3] They are the largest known Asian troodontids, with a skull length of 27.2 cm (272 mm). At the time of the discovery of the genus, the only other troodontids that appeared to be larger than it were specimens from Alaska,[2] however, Latenivenatrix are now considered the largest troodontids with 3.5 m (11 ft) in length.[4] The preserved vertebrae in IGM 100/1 are completely fused, indicating that this individual was an adult at the time of death.[2]

ClassificationEdit

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

Life restoration
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.[5]

Paraves 
 

Avialae

 
 Deinonychosauria 
 

Dromaeosauridae

 
 Troodontidae 
 

Sinovenator

 
 
 

Anchiornis

 
 
 

Mei

 
 

Talos

 
 
 

Byronosaurus

 
 
 

IGM 100/44

 
 

Sinornithoides

 
 
 
 

Linhevenator

 
 

Philovenator

 
 
 
 

Gobivenator

 
 
 

Troodon

 
 
 

Saurornithoides

 
 

Zanabazar