Bagaraatan ostromi, Osmolska, 1996
Holtz, TR jr., 2004, Tyrannosauroidea, The Dinosauria, University of California Press, pp. 111-136 : 8
publication ID |
https://doi.org/ 10.5281/zenodo.3374526 |
DOI |
https://doi.org/10.5281/zenodo.3483196 |
persistent identifier |
https://treatment.plazi.org/id/012B87ED-FF8B-D81A-4DBE-25F2DC97B66C |
treatment provided by |
Jeremy |
scientific name |
Bagaraatan ostromi |
status |
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is known only from a partial mandible, a partial pelvis, an incomplete hindlimb, a partial sacrum, and most of the caudal series from the Late Cretaceous of Mongolia (Osmólska 1996). It is apomorphic in its two caudal surangular foramina and stout hyposphene-hypantrum articulations in the first 16 caudals. As in some ceratosaurs and birds, the astragalus and calcaneum are fused to each other and to the tibia; furthermore, the distal portion of the fibula is fused to the tibia and tarsus. Osmólska (1996) did not attempt a phylogenetic analysis of this taxon but hypothesized that it was the sister taxon to Avetheropoda . Here it is found to be closer to Tyrannosauridae , and hence a basal tyrannosauroid, as well as to related taxa based on the following derived features: a prominent and laterally extending horizontal shelf on the lateral surface of the surangular, rostral and ventral to the mandibular condyle; the retroarticular process reduced and broadened; and a ventral flange on the ischial peduncle of the pubis. However, given the fragmentary nature of this taxon and the incomplete nature of what is known of B. ostromi , such a position is not particularly secure and is likely to change with new information.
The remaining diagnostic characters for Tyrannosauroidea unite a clade composed of Stokesosaurus , Dryptosaurus , and the Eotyrannus - Tyrannosauridae group.
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