Copepteryx is an extinct genus of flightless bird of the family Plotopteridae, endemic to Japan during the Oligocene living from 28.4—23 mya, meaning it existed for approximately 5.4 million years. The name is derived from the Greek words "Kope pteryx" meaning oar wing. The apparent reference to the 19th Century Paleontologist Edward Drinker Cope is accidental. Copepteryx was a diving plotopterid bird which is similar to the Waimanu.