I love that film so much
I remember reading about some of the concepts right at the start of the production, originally almost all the effects were going to be physical, guys in suits, animatronic etc, but Spielberg wasn't happy with the movement in the wide shots, so Dennis Muren pitched a small CG dino test, and nailed it first go. Most of the physical effects stayed, but the CG allowed them to vastly build up the ecosystem, and get some shots which were just too difficult otherwise..
Still can't believe they made that full-size T-Rex though..
Men in Dino-suits! - http://www.youtube.com/watch?v=jAzQr3Ml ... e=youtu.be
It came back the other way a little, with the DID (Dinosuar Input Device), which let the puppeteers control or guide the CG animation - very neat