Named By: Efremov - 1954.
Classification: Chordata, Synapsida?
Species: P. aenigmaticum (type).
Known locations: Russia.
Time period: Roadian of the Permian.
Fossil representation: Single femur.
Because Phreatophasma is known only from a single femur (upper leg bone), there is great uncertainty about what kind of animal Phreatophasma actually was, with suggestions ranging from it being a pelycosaur to parareptile. Most researchers consider Phreatophasma to be a nomen dubium.