The Plesiosaur Project - from discovery to display

an amazing discovery | the outback today | Coober Pedy - back to the Cretaceous |
The Addyman Plesiosaur - a national treasure | The Plesiosaur Puzzle |
Plesiosaur Birthing Ground | Skin Deep - making the plesiosaur model

The Plesiosaur Puzzle

Piecing together the fossil was a slow but enjoyable task for Mr Kear. He likened the project to a giant jigsaw puzzle. "There is nothing mysterious about putting the fossil together. It's simply looking at colors, shapes and piecing things together. After a while you tend to work out what bone you've got and use your knowledge of anatomy to know what bits you're looking for.''

Ben Kear working on the plesiosaur jigsaw puzzle in the Origin Energy Fossil Gallery.

There is 36kg of opalised skeleton to be cleaned and assembled. One of the more vital parts, the skull, is missing.

Large opalised fossils are extremely rare. Normally, smaller creatures are preserved this way or only fragments such as jaws are found.

"To get more than just a few bones is extremely rare. There's probably only 10 to 20 skeletons around Australia in various degrees of completeness.''

Why is the Addyman plesiosaur skeleton incomplete?

The head, much of the neck and three flippers from this plesiosaur were never found, and the one remaining flipper was discovered well away from the rest of the body bones.

It appears that after the body sank to the sea floor, waves or scavengers fragmented the skeleton before it was buried by muddy sediment.

Diagram showing the complete skeleton of the plesiosaur.

How old is the Addyman plesiosaur fossil?

The Addyman plesiosaur is estimated to be about 115 to 120 million years old. We know this because it was found with fossils that occur only in sediments of the Aptian Stage, of the Early Cretaceous Period (65-145 million years ago).

The Addyman plesiosaur came from the Bulldog Shale. This thick accumulation of grey-green mudstone was deposited in the Eromanga Sea, which covered the eastern interior of the continent in the Cretaceous Period.

Dinosaurs and other reptiles lived on the land at the same time that plesiosaurs lived in the sea.

Timeline The age of the Solar System is at least 4500 million years (my). 3500 my ago there were bacteria living in the oceans of the Earth. It took almost 3000 my for large animals and plants to evolve on Earth. The Origin Energy Fossil Gallery will highlight evidence of life found in the rocks of South Australia for the last 600 my of Earth history. The Ediacaran and Cambrian periods represent the time when complex animals evolved in the ocean. In the Cretaceous Period, much of inland Australia was covered by a shallow sea inhabited by marine reptiles like the plesiosaurs while dinosaurs roamed on the surrounding land. The Pleistocene Epoch represents the time when the last of the megafauna thrived in Australia. These giant animals included marsupial mammals, reptiles and birds.