Imagine giant marine reptiles 10 metres long living and thriving in icy inland seas where there is now only desert.
The opal fossils gallery brings these imaginings to life with spectacular opalised fossils from Coober Pedy and Andamooka in the state's north.
The centrepiece of the gallery is literally a jewel: the opalised skeleton of a six metre long Addyman Plesiosaur. This priceless specimen was found in an opal mine in Andamooka in 1968. It is the finest known opalised skeleton on Earth.
Other exhibits in the opal fossils gallery include a piece of ancient seabed with several hundred opalised shells, fossils from the moon plain north of Coober Pedy, and the largest ammonite ever found in Australia, which was originally mistaken for a truck tyre.