Yep freyar, these are indeed shoveling animals. And despite their enlarged jaws, their bite force isn't really strong, so they can't, say inflict a vorpal bite, or even clamp down with Improved Grab. (As herbivores, they don't need too much force to eat mulch. )
Vegetation Bite (Ex): The bite of an amebelodon ignores the first 10 points of hardness of any plant matter, including anything made of wood as well as plant creatures.
I dunno. The bite's not got much force behind it--it's not eating trees, it's scooping up marsh plants. Not much you can do for an animal with a diet of sludge, except a bonus on Fortitude saves...
We could put a spin on the mammoth's toss ability like so...
Toss Muck (Ex): As a standard action, an amebelodon can toss a tuskful of muck at a target within x feet. This requires a ranged touch attack. The target is blinded until it takes a move action to wipe off the muck.