"The troodontid Byronosaurus jaffei is known from two specimens from adjacent localities in the Nemegt Basin, Mongolia. These specimens are composed of well-preserved cranial material and fragmentary postcrania. Byronosaurus jaffei is included in a comprehensive phylogenetic analysis of Coelurosauria to ascertain its relationships. Several interesting characters of Byronosaurus jaffei have implications both for theropod relationships and for understanding patterns of variation within coelurosaurian theropods. These include the position of a foramen that marks the exit of the supra-alveolar canal (which we suggest is homologous with the subnarial foramen), the flattened internarial bar, the unusual interfenestral bar, and the unserrated teeth. Additionally, the well-preserved braincase allows detailed comparison with other troodontid taxa."

CT scans of the rostrum of IGM 100/983.

This specimen, the holotype, which consists of a rostral fragment, braincase, and several postcranial pieces, was collected from the Upper Cretaceous Djadokhta Formation of Ukhaa Tolgod, Mongolia. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Mark Norell of the American Museum of Natural History. Funding for scanning was provided by an NSF grant to Dr. Norell.

The rostrum of the holotype specimen IGM 100/983 in right lateral and dorsal views.

This specimen was scanned by Richard Ketcham in May 1997 along the coronal axis for a total of 562 slices. Each slice is 0.25 mm thick, with an interslice spacing of 0.25 mm. The x and y spacings were estimated because the field of reconstruction was not recorded.

Literature
Mackovicky, P. J., M. A. Norell, J. M. Clark, and T. Rowe. 2003. Osteology and relationships of Byronosaurus jaffei (Theropoda: Troodontidae). American Museum Novitates 3402:1-32.

Norell, M. A., P. J. Makovicky, and J. M. Clark. 2000. A new troodontid theropod from Ukhaa Tolgod, Mongolia. Journal of Vertebrate Paleontology 20:7-11.

None available.