Oviraptor
Oviraptor is usually drawn with a distinctive crest, similar to that of the cassowary. However, re-examination of  several oviraptorids show that this well-known, tall-crested species may actually belong to a relative of Oviraptor, the genus Citipati. It is likely that Oviraptor did have a crest, but its exact size and shape are unknown due to crushing in the skull of the only recognized specimen.