The ancient now-underwater continent of Zealandia may have been home to plants and animals more recently than first thought, scientists say.
Zealandia, which was confirmed as the world’s seventh continent earlier this year, remains shrouded in mystery because most it is submerged in the Pacific Ocean.
On Wednesday, scientists shared their findings in Hobart following a two-month sea expedition which surveyed the region in unprecedented detail.
Zealandia was thought to have gone underwater about 80 million years ago when it separated from Australia and New Zealand.
But Professor Rupert Sutherland from the Victoria University of Wellington in New Zealand said sediment samples showed parts of the continent rose when volcanic activity created the Pacific Ring of Fire about 50 million years ago.
“Water that was once very deep when the dinosaurs were around became shallow again,” he said.
“We had possible seaways, even islands that plants and animals could have migrated along, things likes ferns for example.
“We thought previously that Zealandia sank, disappeared under the ocean in the Cretaceous.”
Sediment samples were extracted from nearly five kilometres below sea level by the crew of JOIDES Resolution, a 1970s-built oil drilling ship converted for research purposes.
Some 30 scientists including a handful of Australians were onboard for the mission as part of the International Ocean Discovery Program.
They drilled at six sites in an area roughly the size of India, retrieving 8000 specimens and several-hundred fossil species.
“The most exciting thing about this is it reminds us that there is still a lot of basic exploration to do on our planet,” IODP director Brad Clement said.
“This ship gives us the opportunities to actually put our hands on sediments and rocks.
“We’re learning fundamentally new things.”
JOIDES Resolution, which costs $US150,000 ($A190,635) a day to run, is part of a three-pronged team including a Japanese drilling ship and scientists in Europe.
Zealandia sediments samples will be further analysed in America early next year.
The continent is roughly five million square kilometres and includes New Caledonia and New Zealand.
Prof Sutherland said the samples would also give valuable insight into how the earth’s climate had changed over millions of years.
“Going back and looking at the records is the way to understand the greenhouse climate systems,” he said.
“Zealandia holds a fantastic record of those processes.”
JOIDES Resolution is embarking on five expeditions in Australian and New Zealand waters over the next year.
It is being re-stocked with food and supplies and will leave Tasmania on Sunday for further ocean drilling off Australia’s southwest coast.
© AAP 2017