Variation, Variability, and the Origin of the Avian Endocranium: Insights from the Anatomy of Alioramus altai (Theropoda: Tyrannosauroidea) Bever, Gabe S. ; Brusatte, Stephen L. ; Balanoff, Amy M. ; Norell, Mark A. Abstract Publication: PLoS ONE Pub Date: August 2011 DOI: 10.1371/journal.pone.0023393 Bibcode: 2011PLoSO...623393B