|MEANING||Informal name, after the Addyman family|
|AGE||Early Cretaceous 120 MYA|
|LOCATION||Andemooka, South Australia|
In 1968 John and Molly Addyman (greengrocers by trade), took up opal prospecting. On almost the first day they discovered an opalised plesiosaur skeleton in an abandoned mine shaft at Andamooka, in South Australia. They kept the fossils for thirty two years, first in a bank vault, and then in their house. It is comprised of 36 kg of potch opal. The newspaper "The Advertiser" bought the plesiosaur fossil for $25,000 and donated it to the South Australian Museum. It was prepared by Ben Kear in a special public display room at the South Australian Museum, sponsored by Origin Energy, and a mounted display has since been created by Jo Bain, a taxidermist with the museum. The prepared fossil proved to be around 15-20% complete. Other opalised remains on display at the museum include the skull of a baby ichthyosaur and the partial skeleton of a baby plesiosaur.
The Addyman plesiosaur appears to represent a type of plesiosaur previously unknown, which has yet to be named. Skeletons like this are no longer recovered from Andamooka, since machines have replaced the pick and shovel and fossils are broken and destroyed in the new mining process.
When alive, the Addyman plesiosaur would have measured about 6.5 metres in length, and swam in the Early Cretaceous seas of South Australian about 120 MYA. At the time Australia had a vast inland ocean, the southern reaches of which would have had ice bergs at certain times of the year.
Up to 95% of marine reptile remains in S.A. are from juveniles. The area is thought to have been a birthing ground for plesiosaurs and ichthyosaurs. They may have been attracted to the colder waters because they would have been teeming with plankton, small fish and squid.
One juvenile skeleton can be attributed to the small (3 metre) freshwater/ estuarine pliosaur genus Leptocleidus. The material comprises a partial skeleton with skull fragments, a nearly complete neck, partial pectoral and pelvic girdle and nearly complete humerus and femur. The specimen was purchased by the museum in 1967 and comes from the Aptian Bulldog Shale deposits of Andamooka. A description of this specimen has been submitted for publication in the European palaeontology journal Lethaia and is currently in review." (Ben Kear 2001)
See the South Australian website at www.samuseum.sa.gov.au/plesiosaur/ for details on how the plesiosaur was prepared.