Liopleurodon rossicus is known from the early Tithonian (Volga Beds) of Russia. Liopleurodon was a powerful swimmer. Its four-flipper mode of propulsion is characteristic of all plesiosaurs and pliosaurs. A study involving a swimming robot has demonstrated that although this form of propulsion is not especially efficient, it provides very good acceleration – a desirable trait in an ambush predator. The average size of the Liopleurodon would have ranged up to 10 metres (33 ft) long.