 Later in the same paper he proposed that Tyrannosauridae be defined as " all descendants of the most recent common ancestor of Tyrannosaurus and Aublysodon . " He also criticized definitions previously proposed by other workers , like one proposed by Paul Sereno , that the Tyrannosauridae was " all taxa closer to " Tyrannosaurus " than to Alectrosaurus , Aublysodon , and Nanotyrannus . " Holtz observed that since Nanotyrannus was probably a misidentified T. rex juvenile , Sereno 's proposed definition would have the family Tyrannosauridae as a subtaxon of the genus Tyrannosaurus . Further , his proposed definition of the subfamily Tyrannosaurinae would also be limited to Tyrannosaurus . 
