Curious. Do any of you know exactly what went into that sound? I've heard a variety of things, namely elephants, lions and washing machines; I imagine it might be a combination of all three.
The rumor I heard is that it was a baby elephant that had been taken away from it's mother... Don't know how true that is...
Gary says one element is a Koala Bear. Other elements are lions, tigers, alligators, and yes a baby elephant from Marine World. He used a whale's blowhole for the breathing.
Then he loaded them all on a synclav and played them so they were in the same key. This made them mesh well together.
I also know that the Veloceraptor is a walrus and dolphin scream mixed together.
They went out and recorded a T-Rex.... duuuuuuuuhh..........
Ryan is right. Koala bear, alligator, a whale, lizards, etc...
Here's a great interview with Gary about it:
Aside from what sounds went into creating the T-Rex roar (which is one of my favorite movie sounds ever - Gary Rydstrom FTW!) is how it was mixed. Whether intentional or not, and I'm guessing it was, the roaring is distorted, almost as though the dino would have overloaded the mic on the set or the mixer wouldn't have been able to adjust for it. The only thing I would have done differently to emphasize this overloading effect would be to side-chain the roar to a heavy compression on the other tracks. I've always wanted to try that on monsters, bullets, explosions, etc.
Here's a recent article about Jurassic Park sound design: