Momma Dino is a main character and is originally believed to be the villain, since she takes Sid and the Baby Dinos. However, later she saves Buck and the gang by pushing the real villain, Rudy, off a cliff. earlier on, she also helps Sid, proving that she's not actually a villain. The Baby Dinos are also T-rexes, since they are Momma Dino's babies.
Secondly, on The Plates of Woe, the raptors the gang encounter are actually Guanlongs. Manny crushes several of these while fighting them, to protect Ellie, who is having a baby. Diego also helps Manny.