Though A. crassicostatus is probably a junior synonym for Adriosaurus suessi, A. tommasinii was found to be similar to coniasaurs, mosasauroids, and a sister taxon to modern snakes in 2010.

[1] The primary portion of Acteosaurus' name comes from Actaeon (/ækˈtiːən/; Greek: Άκταίων), a famous Theban hero who was hunted and killed by the goddess Artemis.

The type species was named after the botanist Muzio Giuseppe Spirito de Tommasini (1794—1879), the Podestà—or magistrate—of Trieste under the Habsburgs.

[4] Its shortened forelimbs and long tail help to distinguish it from other genera, and its vertebral column is similar to more modern varanid lizards.

[1] Both Acteosaurus tommasinii and A. crassicostatus were found in the upper section of karst Cenomanian platy limestone, in Komen, Slovenia.