"You are what you eat." This is true not only for humans,
but extinct mastodons as well. Scientists have drilled holes in
the teeth of both the Hyde Park and Gilbert Mastodons and are
analysing the chemistry of these cuttings. As an amimal eats,
certain chemical ratios of the food he/she eats becomes incorporated
into the animal's bones and teeth. It is therefore possible to
determine, for example, whether or not an extinct animal ate meat
or was strictly vegetarian. Isotopic ratios from the Gilbert Mastodon
reveal that this animal ate more than just grass - this animal
was a browser, eating spruce twigs and other vegetable matter.
There are those that speculate that Cornell's Gilbert Mastodon
was possibly a scavenger (a case made stronger by the serated
teeth of the mastodon, as well as soem of the isotopic numbers
from the teeth), but this is, at this point, still purely speculative.