Orcinus citoniensis is an extinct species of dolphin belonging to the family Delphinidae that lived from 2 to 5 million years ago in the Pliocene. The now-extinct species was related to the modern killer whale. It was described based on an incomplete skull found in Italy, which lacks the rear and left side, but had the back side. It had 28 teeth in each jaw, unlike the current orca which has on average 24 teeth in each jaw. This specimen could be 4 metres long and had the appearance of a small killer whale, so it could be a transitional species between early dolphins and the modern killer whale.