Extract from ABC News
Mike Thomson was mapping rock layers on the Antarctic Peninsula when he unearthed the bone. (Supplied: British Antarctic Survey)
In short:
Dinosaur fossils are extremely rare in Antarctica.
But a bone found there in 1985 and kept in a drawer for almost 40 years has now been confirmed as the first of the dinosaur fossils to have been discovered there.
What's next?
Scientists say the find sheds light on the spread of dinosaurs across the planet's southern continents millions of years ago.
In December 1985, geologist Dr Mike Thomson was mapping rock layers on the Antarctic Peninsula when he unearthed a bone.
The meticulous notetaker pulled out a pencil and jotted down his initial thoughts about the fossil.
"Vertebra of large reptile," he wrote in his field diary, alongside a sketch of the 10-centimetre-wide bone.
Mike Thomson on James Ross Island on the Antarctic Peninsula in 1985. (Supplied: British Antarctic Survey)
Along with other specimens found during the expedition, the bone was sent to the British Antarctic Survey's (BAS) geology collection in England.
It remained there, unidentified and hidden inside a drawer, for almost 40 years.
Mike Thomson was a meticulous note taker, and recorded details of the fossilised bone. (Supplied: British Antarctic Survey)
That was until BAS collections manager Dr Mark Evans, who has a background in vertebrate palaeontology, took a closer look.
"When I first spotted this bone in our collections a few years ago, I suspected it was a dinosaur," Dr Evans said in a media release issued by BAS.
The dinosaur bone was kept in a drawer for 40 years. (Supplied: British Antarctic Survey)
Dinosaur fossils have been found in Antarctica over recent decades, but they are extremely rare.
In fact, of all the continents, it has the fewest records, largely because of its extensive ice cover.
But there was something about the distinctive shape of the vertebra that intrigued Dr Evans.
"After looking at it properly, I thought it was probably a titanosaur tail vertebra,"he said.
Storage boxes for specimens like the Antarctic dinosaur bone. (Supplied: British Antarctic Survey)
His theory has now been confirmed, meaning the fossil found on James Ross Island in 1985 was, in fact, the first of the dinosaur bones to be discovered in Antarctica.
"Looking back at Mike's notebooks, he knew it was a large reptile so it's very special to confirm his find 40 years later,"Dr Evans said.
The bone is believed to be from a titanosaurus, recreated by an artist here. (Supplied: Andrew McAffee Carnegie Museum of Natural History)
Bone comes from largest type of dinosaur
Titanosaurs were the largest of the dinosaurs to live on land, with some measuring more than 35 metres in length, and weighing more than 15 tonnes.
"It [was] a big, long-necked, long-tailed … type [of] dinosaur, a bit like … brontosaurus," Dr Evans said in a video posted on YouTube.
The bone is thought to have come from a relatively small, or juvenile, titanosaurus about 6 or 7 metres long.
"So they are absolutely huge animals and this is quite a small one by comparison,"Dr Evans said.
The bone was found in a marine rock layer dating back about 82 million years.
At the time, Antarctica was very different from the icy continent it is today.
"It was a heavily forested area, it was warm, it was temperate like the rest of the planet," Dr Evans said.
Scientists believe the animal floated out to sea after its death, before eventually being buried and fossilised on the seabed, BAS said.
The fossil was the first dinosaur bone to be found in Antarctica. (Supplied: British Antarctic Survey)
Professor Paul Barrett, a researcher at London's Natural History Museum, said the find sheds light on the spread of dinosaurs across the southern continents.
"To date, no titanosaurs have been found in Australia, and there is only limited evidence of them in New Zealand,"Professor Barrett said.
"Confirmation of the presence of these animals in Antarctica makes it seem likely that they travelled on to these areas, which were connected."
BAS said researchers believe there is likely to be more evidence of dinosaur records in Antarctica, which could emerge as the ice retreats.
'Needle in a haystack'
Associate Professor Steven Salisbury, from the University of Queensland's Dinosaur Lab, said only about a dozen dinosaur fossils had been found in Antarctica.
"The reality is down there you are really searching for a needle in a haystack," Dr Salisbury said.
Steven Salisbury says the find is "an important piece of the puzzle". (ABC News: George Roberts)
While Dr Salisbury was not involved in the research surrounding the titanosaur fossil, he has previously undertaken several dinosaur fossil hunts in the polar region.
"To find the fossils of a terrestrial animal like a dinosaur [in Antarctica], you're counting on the fact that a dinosaur has died somewhere on the coast or near a river and that somehow its carcass has found its way out into this shallow seaway, has not been too badly scavenged and then has somehow made it to the bottom to get buried.
"And then you're stumbling across it as you're trudging through the snow and ice, 80 million years later.
"When you start to think of it like that, you begin to realise your chances are pretty slim and it is really just luck and spending the time there."
Dr Salisbury said confirmation that Dr Thompson's 1985 discovery belonged to a titanosaur was "significant".
"Not only has it extended our timing of recognition of dinosaurs in Antarctica, but it's added to the very sparse record that we do have," he said.
"So even though it's not the most spectacular of fossils, it is an important piece of the puzzle."
