• Find out all about the long-necked plesiosaur (above) and other scary reptiles in the Fremantle exhibition Sea Monsters.

A NEW exhibition in Fremantle reveals sharks weren’t always top of the ocean food chain and fought ferocious battles with 13-metre long sea monsters.

It may sound like something out of a Godzilla movie, but once you lay eyes on the giant life-size skeletons at Sea Monsters: Prehistoric Ocean Predators you’ll be convinced how scary these ocean leviathans were.

Featuring more than 70 exhibits including a 13-metre long elasmosaurus, nine-metre prognathodon and a huge 1.4 metre kronosaurus jaw, the immersive and interactive exhibition whisks you back about 80 million years, when giant reptiles ruled the waves.

Dr Mikael Siversson, head of earth and planetary sciences at WA Museum Boola Bardip, says there’s a great life-size cast of a mosasaur, which was the apex predator at the time and could grow up to 13 metres long.

“They were absolutely brutal reptiles with a big head and whopping teeth, and featured in the Jurassic World movies,” he says.

“There were lots of sharks around at that time and there’s evidence of epic battles between them and mosasaurs.

“There’s a fossil in Kansas of a five-metre mosasaur that was bitten in half by a very large shark.

“Eventually the mosasaurs became bigger and bigger and dominated the sharks.

“But after the mosasaur became extinct, the sharks bounced back and that gave rise to the famous megalodon.”

Dr Siversson’s favourite exhibit in Sea Monsters is the skeleton cast of the long-necked plesiosaur, which ate cephalopods and fish, and could grow up to about 12 metres.

“The body shape on those creatures is unlike anything you would see today,” he says.

“They have a stocky body, four huge flippers and an enormously long neck. It’s totally unique.”

“We have fossils of long-necked plesiosaurs and I think the closest found near Perth was in Dandaragan.”

The exhibition also includes an incredible specimen of an ichthyosaur, a large extinct marine reptile, giving birth and a five-metre-long fish that died after swallowing another fish whole.

So could these scary sea monsters ever be resurrected using DNA or is that the stuff of La La Land?

“That’s fantasy,” Dr Siversson says.

“Strands of DNA can survive for hundreds of thousands of years and they’re trying to resurrect the Tasmanian tiger, but going back millions and millions of years is a bit Hollywood.

“But in terms of how these three groups of sea monsters relate to living animals: Mosasaurs belong to the same group as snakes and lizards, whereas the ichthyosaurs and the plesiosaurs are dead in evolutionary terms and not closely related to any living reptiles.”

Sea Monsters: Prehistoric Ocean Predators is at the WA Maritime Museum, Victoria Quay Road, in Fremantle until Sunday July 16.

And if you want to find out even more, WA Museum Boola Bardip has a whole section devoted to fossils of sea monsters from the cretaceous period (between 145.5 and 65.5 million years ago).

by STEPHEN POLLOCK