What's the first thing Spike does when he's born? He eats his own nest. This is a sign of things to come.
Petrie deciding that he can stay on Littlefoot's head and hang onto his tree star, accompanied by him rolling the tree star up, holding it like a bayonet, and marching back and forth on Littlefoot's head.
Cera's snark provides a lions share of the humor in the sequels and TV series.
When Chomper claims his parents would like the gang, Cera replies: "How? Rare, medium, or well done?"
"If there's one thing I will not tolerate, it's violence" "Then why did you hit me?"
"Right, make that two things. Violence and stupid questions! *hits him again*
In VIII, as the gang hikes through deep snow, Littlefoot mutters 'How could this get any worse?'. Cut to the gang struggling through a blizzard as Cera shouts 'You had to ask, didn't you?!'
Cera's reaction to finding out the Great Valley dinosaurs may have to split back into seperate herds: "I don't wanna live with a bunch of three horns! They're way too bossy!"
In IV, Icky gets stuck in a log so Dil chomps him out of there, so his neck is only stuck in part of the log. He panics when he thinks Dil is going to eat him, but Dil bites off the last part of the log. After the log is gone, the look on Icky's face is priceless.
This troper always got a chuckle out of Spike's scat-singing.
In one episode where the gang is looking for sky colored stones (geodes), the episode's 'villain' is Ducky. She goes from being the nicest person in the show to a greedy, deceiving, paranoid hoarder who would rather hunt for gems than help her stuck brother. This can be seen as either hilarious, disturbing, or both.
In the TV series, they find a talking crab who enjoys telling stories. Cera comments: "Great. Not only does he talk, he talks too much."
In the same episode, after almost drowning to get some seaweed, Cera emerges from a whirlpool covered in kelp fronds. Petrie says: "You got the water greens!" To which Cera replies: "Yes, now GET THEM OFF ME!"