Despite having voiced the loveable sloth Sid in two previous Ice Age films, comedian John Leguizamo found that he had to prepare himself to voice the character in the third film, Ice Age: Dawn of the Dinosaurs:
I've got to walk around the house a lot the day before, working on the lisp so that it's not too much, that it's just right.
Sid's a vulnerable character, with a higher-pitched voice than you'd think. So I have to tighten up, get the voice up there so that he doesn't sound like a sloth who's been out partying all night.
In addition to Leguizamo reprising his role as the voice of Sid, Ice Age: Dawn of the Dinosaurs features the return of Ray Romano as the voice of Manny, Queen Latifah as Ellie, and Denis Leary as Diego.