Plutoniosaurus was named by Vladimir Efimov in 1997 based on the holotype specimen UPM 2/740, a partial skeleton. In 1999, Maxim Arkhangel'skii synonymized the genus with Platypterygius, as did Michael Maisch and Andreas Matzke in 2000.
Plutoniosaurus was first named by Vladimir Efimov in 1997 from the holotype UPM 2/740, however, it was subsequently synonymized with Platypterygius by Maxim Arkhangel'skii in 1999 and later confirmed by Michael Maisch and Andreas Matzke in 2000.