Why would anyone think Ali is fast? Certainly, neither she nor Littlefoot are as fast as petrie or Ruby. I believe that Petrie is the fastest overall, but Ruby is the fastest on the ground. We have no reason to believe that Ali, Littlefoot, Cera, Ruby, or any of the dinosaurs or peterosaurs had good endurance. Over a distance, I'd say Ruby would still be fastest on the ground, and Petrie the fastest in the air (and Mo would be the fastest in the water, but excluding him, the only possible answer is Ducky.)
EDIT: Keep in mind that migrating animals aren't necessarily faster than non-migrating ones; cheetahs are still faster than migrating wildebeests. We also have no idea how much intense exercise Ali gets; Littlefoot and his friends have had to do a lot of running, but we don't know if the same applies to Ali.
