Rewind 460 million years to a time when most of Australia was under water and aquatic creatures swam freely above what is now the dry dusty landscape of Central Australia.
- The Central Australian landscape was once a vast ocean and home to the Endoceras, an oversized killing machine which preyed on fish species and trilobites
- The giant nautiloid was about two-and-a-half metres long
- It propelled itself at vast speeds through the water 460 million years ago during the Ordovician period
Dr Adam Yates, senior curator of Earth Sciences for the Museum and Art Gallery of the Northern Territory, said that it was a time before any dinosaurs or any animal with a backbone lived on land.
He said the oceans of the Ordovician period were home to the Endoceras, an oversized killing machine which resembled a giant unfurled nautiloid and preyed on early fish species and trilobites.
"It is probably not widely recognised amongst our ordinary everyday people that Central Australia was home to these marine animals and their fossils can still be found in places like the MacDonnell Ranges."
Largest animal alive
Several years ago Dr Yates came across a section the Endoceras when the museum shifted premises.
"This particular fossil was found lurking in the basement of the old space where the collection was temporarily stored for many years before we finally moved into the new museum at Megafauna Central in the centre of Alice Springs.
At closer inspection Dr Yates realised that significance of the specimen.
"It came from an exceptionally large nautiloid," he said.
"It would have been about two-and-a-half metres long, which makes it one of the largest animals alive at the time.
"The segment of fossil that you see is only a part of the whole creature," he said.
At one end there would have been the body chamber and at the other would have been a shell tapering off to a point.
"The back part of the shell, which this [segment] is a part of, was filled with gas chambers, which they can use for buoyancy control so they could float up and down at will," Dr Yates said.
Dr Yates said these creatures had some similarities to a modern squid.
"In amongst this crown of tentacles right at the centre they have a parrot like beak that they use for tearing open prey and eating with.
"Not only that they have a funnel so that when they want to move very quickly, they can expel water from their gill chamber, out that funnel and basically jet propel themselves backwards," he said.
Survival of the fittest
Dr Yates said the ancient nautiloids no longer existed, thanks to evolution.
"If you took a modern nautilus and you unfurled it — straightened it out — so it became a cone, instead of a ram's horn, then you would have an animal like the extinct Endoceras," he said.
According to Dr Yates lugging a giant straight cone became a disadvantage.
"During their evolution the coiled nautiloids were more successful," he said.
"It was much, much more efficient to coil it up. So you don't have to carry this great big long shell dragging behind you."