I noticed in movie 4 that the Longneck herd almost sounded like cows when they were first arriving. In movie 5, that T-rex roar almost sounded like an elephant.
I'm wondering, which of the main characters CAN make a noise?
So far, I think I can guess the following:
Chomper - roaring (though perhaps not the best at his current age)
Cera - that weird screech of hers (though she has only used it in the first few films)
Petrie - possibly he can make the same noise as that Pteranodon did in the 2nd movie when she chased off Ozzy and Strut.
Ducky - Unknown
Spike - Unknown
Littlefoot - Might be able toi sound like a cow. Also, i thought his mother made some weird sound when fighting Sharptooth.
Ruby - unknown
Sierra - think he had one too (or at least the wiki said he did.)