Oviraptor

Long mistaken for an egg thief, Oviraptor philoceratops was named for a skeleton found atop a clutch of eggs, which early workers assumed to be its prey. Later discoveries of similar animals brooding their own nests overturned that interpretation. About 1.6 meters long and near 33 kilograms, this omnivore had a short, toothless beak and a distinctive crest on its skull. Henry Fairfield Osborn described it in 1924 from the Gobi Desert of Mongolia, where it lived during the Late Cretaceous, roughly 100 to 66 million years ago. It has become a textbook example of how the meaning of a fossil can be revised as evidence accumulates.