Suppose you found the bones of an unidentified animal. How could you learn about what the animal ate? What specific structures would give you clues about the creature’s diet?
There are multiple ways to identify the diet of an animal after death. One way to find key identifying clues would be to study the animals dentition; this is the development and arrangement of teeth. There are two types of animals (as far as teeth categorization goes); homodonts and heterodonts. In the mouth of a homodont, all the teeth are the same shape and makeup (with the exception of fangs in some reptiles). In the mouth of a heterodont however, one will find many different types of teeth; like in humans. The shape and makeup of each tooth can then be used to narrow down and determine its specific function, and the animal to which it belongs. Sharp long teeth are used for tearing, shredding and getting a good grip on flesh; whereas flat, blocky teeth are used to grind and mash plant matter. It take more effort to break down the cell wall in plants, so smashing up the food allows for the most surface area to be exposed at a time.
Extra: If one had found a carcass with fresh-ish remainders still inside, (obviously unlikely, but…) they would be able to come to the conclusion about the animals diet based upon the length of the intestines as well. Herbivores have a longer small intestine than carnivores; this is because they are maximizing the amount of surface area being exposed and processed at once. Plant matter is more difficult to digest than animal flesh.
Humans have intestines (for the most part) that are, lenghtwise, in-between that of carnivores and herbivores; surprisingly, length can vary by as much as five feet between two people, but nonetheless, humans have the build of an omnivore.