Ƙananan sanannun mutum (LACM 28471, "Jordan theropod") an kiyasta cewa yana da nauyin kilo 30 kawai (66 lb), yayin da mafi girma, irin su FMNH PR2081 (Sue) ya fi dacewa kimanin kilo 5,650 (12,460 lb). Nazarin ilimin lissafi na ƙasusuwan Tyrannosaurus rex ya nuna LACM 28471 yana da shekaru 2 ne kawai lokacin da ya mutu, yayin da Sue ya kasance shekaru 28, wanda zai iya kasancewa kusa da iyakar ga jinsin Tyrannosaurus. Halitta ya ba da damar ƙayyade shekarun sauran nau'o'in. Za a iya ƙayyade shekarun girma a lokacin da aka samar da nau'o'i daban-daban na dabbobi tare da plateaus daban-daban.
matashin Tyrannosaurus rex