What benefits would this feature have?

Question

http://en.wikipedia.org/wiki/Image:Dinotherium.jpg

The downward pointing tusks, what good were they?

Surely they presented many hazards?

Answer 1

It became EXTINCT.

Answer 2

Interesting.  

I'd guess that these tusks could be useful in defending against attacks from below.  

An elephant is a tall animal, so not much will be able to attack it from above.  A lion however, would probably go for the throat, and then these tusks could come in handy.

Answer 3

Handy for digging up tubers or other underground food items, not good for kissing.

Answer 4

Almost certainly for digging up foodstuffs such as roots and tubers.

Possibly, depending on habitat, for clearing away snow to get at food sources at ground level. (Where did these beasties live?)

Also very likely used in display, to assert dominance and so gain priority of access to mates, food sources, etc.. Many features used in such displays are actually designed NOT to injure the animals involved (goal is to assert dominance, not engage in fight in which both animals may be injured). Example would be antlers, which allow male deer to engage in trials of strength, with antler branches (tines?) interlocked but not inflicting too much damage. Another example would be the backwardly-curving upper tusks of male babirusa, which actually grow upwards through the snout.

Perhaps could also be used in defence against, say, crocodile-like predators in the water?