 The precise relationship between this species and the slightly smaller narrow-flippered penguin ("Palaeeudyptes antarcticus") from somewhat younger rocks is not resolved; possibly, "P. marplesi" is a synonym or subspecies of "P. antarcticus".This species is known from a partial skeleton, mainly leg bones (Otago Museum C.50.25 to C.50.45), recovered from Middle or Late Eocene Burnside Mudstone rocks (34-40 MYA) at Burnside, Dunedin, in New Zealand.Many other bones are often assigned to this species.