Zanabazar junior ( Barsbold, 1974 )

Norell, Mark A., Makovicky, Peter J., Bever, Gabe S., Balanoff, Amy M., Clark, James M., Barsbold, Rinchen & Rowe, Timothy, 2009, A Review of the Mongolian Cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda), American Museum Novitates 3654, pp. 1-64 : 28

Zanabazar junior ( Barsbold, 1974)

HOLOTYPE: IGM 100 /1, a skull and partial mandible, six sacral and 11 caudal vertebrae, and the distal part of the right hind limb. The skull is largely complete except for the left and right quadrate, quadratojugal, ventral part of the lacrimal, palatine, pterygoid, and ectopterygoid, and the left squamosal, postorbital, and jugal, posterior part of the right jugal, and the postdentary bones other than the splenials. The posterior part of the left nasal is reconstructed in plaster, as are small parts of the left maxilla anterior to the maxillary fenestra and dorsal to the interfenestral bar. Plaster covers the ventral surface of the bones roofing the antorbital fenestra. The mandible comprises only the dentaries and splenials. The right hind limb includes the distal end of the tibia with the coossified astragalus and calcaneum, a distal tarsal, and the proximal ends of MT II–IV.

TYPE LOCALITY AND AGE: As for Zanabazar .

DIAGNOSIS: As for Zanabazar .

REFERRED SPECIMENS: No new material of this species has been described, but two other troodontids have been described from the Nemegt Formation of Mongolia. Borogovia gracilicrus Osmólska, 1987 , is known only from a partial hind limb from Altan Uul IV, and Tochisaurus nemegtensis Kurzanov and Osmólska, 1991 , is known only from a metatarsus from the Nemegt area. Because the postcranial elements of Zanabazar junior do not include those parts diagnostic of the other two species, it is possible that one of the other two Nemegt Formation taxa is a junior synonym.

COMMENTS: We chose to construct the name Zanabazar for Saurornithoides junior based on the morphological differences between the holotype and that of Saurornithoides mongoliensis and the questionable monophyly of Saurornithoides as defined by the sistertaxon relationship of S. mongoliensis and S. junior . This decision also was influenced by the common practice in phylogenetic analyses of assuming monophyly by compositely coding taxa (especially ‘‘genera’’). The differences between Zanabazar junior and Saurornithoides mongoliensis certainly merit coding these taxa separately. The temporal difference separating these specimens was not, and should not, be used to support taxonomic decisions.