© Stuff.co.nzTop predator of the oceans: An artist's impression of the ichthyosaur.
A scientist has stumbled on the fossil remains of a 'scary' predator, writes Catherine Woulfe.
Scientists have discovered the skeleton of an ichthyosaur - a huge dolphin-like reptile that lived in the time of the dinosaurs - in a Marlborough riverbank.
The fossil is an exciting, significant find, says Wellington palaeontologist James Crampton, who stumbled across it last March. A handful of individual ichthyosaur bones have been found in New Zealand before, but never so many in one place.
This fossil has not yet been excavated from the boulder it was found in, so Crampton is not sure whether it is a complete skeleton, or exactly how big it is. But he can see "loads of bones - maybe 40, 50, 60" - including sections of rib, paddle and vertebrae.
Each vertebrae measures 15cm across.
"In comparison, a cow's vertebrae is about 4cm across, so this thing was really much, much bigger than a cow. This was a big beast."
Most ichthyosaurs were between two and four metres long, Crampton said, but some were bigger than 15m. They were common in the time of the dinosaurs and lived like dolphins, or orca, giving birth to live young, and hunting fish - or each other.
© Stuff.co.nzJames Crampton says this find could help explain an extinction mystery.
They evolved about 250 million years ago and died out about 150 million years later, perhaps because something "better and nastier" wiped them out.
"For a significant part of the time they were on the planet, they were the top predators in the ocean," Crampton said. "They were scary."
This fossil is particularly fascinating to scientists because it died at about the time all ichthyosaurs became extinct. It would eventually help write the "historical diary" for this part of the world, Crampton said.
It is impossible to know how this ichthyosaur died but it could have been attacked by a bigger predator. It then sank to the bottom of the sea and was buried, just off the coast of what was then the super-continent, Gondwanaland. Over millions of years, the sea floor drifted and pushed up to become the surface of New Zealand. Then the river wore down the rock until the bones were visible.
Crampton spotted the bones during unrelated field work in the bed of the Clarence River, in a remote area of Marlborough. He won't say exactly where, as he wants to protect the landowner's privacy.
Crampton was with a team of Italian geologists, who dug the broken boulder out of surrounding mudstone with pickaxes, then hauled it onto a four-wheel-drive. It is now in the lab at GNS Science, where Crampton heads the palaeontology team. Extracting the fossil is an expensive and time-consuming process, and GNS does not have the resources for it.
"It is frustrating," Crampton said. "But it's here, and somebody will [dig it out], someday."
Crampton has published a book to help amateur fossil hunters, The Kiwi Fossil Hunter's Handbook.
It is so scary to see such large vicious predatory beast..........