Question: How did Littlefoot, Ducky, Petire, and Spike get out of the tar?
Question: Why was Cera so mean to Littlefoot?
Answer: Remember her father tells her that the three horns never play with longnecks, so she probably just wants to be with her own kind.
Question: How did Littlefoot's mother die, when she had so few injuries, but the Sharptooth lived after falling the height it fell. At this point in the movie a earthquake happens, splitting the earth open, and creating cliffs. Littlefoot's mother threw the Sharptooth off of the cliff to save Cera and Littlefoot's lives. But falling of a cliff wouldn't just knock you out, it would kill you. The Sharptooth had no ill effects from the fall, except for being knocked out.
Chosen answer: Littlefoot's mother has obvious grievous wounds on her neck and back. She also quite possibly has internal injuries as well. It's also possible that Sharptooth had many injuries as well, but was able to heal better or just fought through the pain because of hunger. Or perhaps he fell in ways that lessened injuries.
Answer: We are not shown how they got out of the tar.