This is a rare sound effect that is not available on the Universal Studios Sound Effects Library. It debuted in the 1960 science fiction film, Dinosaurus!, for the roar of the T-Rex. Part of it is included in Sound Ideas, MONSTER - HUNTING, GROWLING, RUNNING. Links: https://www.youtube.com/watch?v=_Bh1ltSqKz4 https://soundeffects.fandom.com/wiki/UNIVERSAL,_ROAR_-_T-REX_SCREAM#Audio_Samples