Dinosaurs are animals. They have body parts just like any other animal, and different body parts make up different animals. A raven's feather is different from an eagle's feather, and that is different from a tyrannosaur's feather, yet all of these animals are dinosaurs (or were, in the extinct tyrannosaur's case).

By looking at the different body parts of the animal, experts can decide what type of dinosaur is, according to the bones or pieces found (fossils).