This sound effect can be found on Pond5. It probably includes an element that sounds similar to, but should not be confused with a heavily modified version of SoundDogs, Animals-Wild, Big Cats, Tigers - Tiger Roar Growls, and lower-pitched, edited version of second half of Hollywoodedge, Dinosaur Roar Scary S PE980512 (which is the same as Jurassic Park, T-Rex - Attack Roar).