Continuity mistake: When Sid is relaxing in the 'goo' and has it splattered on his face (no-one knows what it is), he wipes his face off with Manny's trunk, none disappearing. In the next shot, the 'goo' has completely disappeared from Sid and the baby.
Continuity mistake: At the end of the movie, where Manny returned the baby, and received the talisman from the human, it was hung from Manny's tusk. As they meet Diego and walk away, the talisman isn't there anymore.
Answer: There are four people who do the voice for the dodos. They are Peter Ackerman, P.J. Benjamin, Josh Hamilton, and Chris Wedge (who also voiced Scrat and directed the movie). I checked their backgrounds, but I did not see any previous cartoons done by them. Also, of the four, it is possible you have seen Josh Hamilton or heard him before, because he has been in quite a few films, but I am not sure he is the one who voiced the dodo who said prepare for the ice age.
T Poston