Ice Age: The Meltdown: There's a flashback where Ellie the mammoth is orphaned in a snowstorm. She's alone and distraught until an opossum with two babies acknowledges her with only the kindest of smiles and decides to raise her as one of the family.
In Dawn of the Dinosaur, when Manny and Ellie's daughter Peaches, was born.
When Manny returns Roshan to his father and is able to reconcile with the hunter in the first film.
For that matter, Roshan and his father reuniting.
Let's not forget the goodbyes between them and Roshan.
The rest of the group pursuing Sid into the land of the dinosaurs, especially considering that Diego is set to leave the herd entirely immediately before. In a similar vein, Diego's first response to Buck's "Sid beat the dinosaur with broccoli" theory being that Sid isn't violent, only adding that Sid also isn't physically capable a moment later, was sweet.