Masracetus was briefly described in an addendum by Gingerich 2007 and is known from just an assemblage of vertebrae and a poorly reconstructed skull from 1908. The lumbar vertebrae are large but relatively short (anteroposteriorly) compared to those of other archaeocetes; the diameter is almost the same as for Basilosaurus isis but the length is less than half of the latter. Masracetus is larger than Cynthiacetus,[3] but it is suggested that the former might be synonymized as a junior synonym with the latter.[4]
The species name honours Richard Markgraf, palaeontologist Ernst Stromer's fossil collector, who collected the type specimen in 1905.[1]