What would be your plot for a "land before time" movie set during the impact that killed off the dinosaurs?

For example, Littlefoot and his gang fleeing the asteroid across the land, fighting off other dinosaurs, picking up allies along the way and making to a deep cave as shelter.
Only little foot makes it inside the cave, and after the impact and the ensuing firestorm is over, he comes out and sees the scorched corpses of his friends, after which he throws himself off a cliff.