In Triassic period of Mesozoic era lakes, seas and oceans were already inhabited by large reptiles, for example, ceresiosaurus were among them – ancestors of plesiosaurus, which appeared in a later Jurassic period. They reached in length 3 m and already had much of the features of a plesiosaurus : long neck, small head and limbs, almost transformed into the fins. They were fast swimmers and propelled in the water like modern penguins do, chasing small and fast prey. Species name means “Lizard from Ceresio” – this is a name of lake on the south of Switzerland, near which fossils of these reptiles were found for the first time.
Ceresiosaurus lived on Earth in the middle Triassic period 230 – 220 millions of years ago and inhabited small coastal lagoons, living alongside with other marine and land reptiles. Form of their limbs tells, that they were able to move on the ground, but not as effective, as other nothosaurus ( animals species, to which ceresiosaurus belong ) did, and already moved to completely marine lifestyle. For the first time fossils of this animals species were found and described in 1931 year by Bernhard Peyer, later people found other fossils of ceresiosaurus in this area.