A modest fossil that sat unnoticed in a drawer for four decades has now been identified as the first dinosaur bone ever discovered in Antarctica.

The fossil was originally uncovered in 1985, but the researchers who collected it were uncertain about its identity. As a result, it was placed in storage within the geology collections of the British Antarctic Survey (BAS) in Cambridge, where it remained largely overlooked.

Recently, palaeontologists re-examined the specimen and confirmed it is a tail vertebra belonging to a Titanosaur — a group that included some of the largest dinosaurs to have ever roamed the planet.

This finding offers valuable insight into how these enormous creatures lived in Antarctica, a region where dinosaur fossils are extremely rare.

Dr Mark Evans, collections manager at BAS, rediscovered the fossil while reviewing thousands of specimens gathered during Antarctic expeditions over many years.

"Sometimes it's only when you start asking yourself, 'What exactly is in this drawer?' that you find something that makes you pause and take a closer look," he explained.

The fossil had been collected on James Ross Island, and its discovery was documented in a field notebook kept by geologist Dr Mike Thomson.

Next to a small, careful sketch dated 9 December 1985, Thomson described it simply as a "vertebra of large reptile" and noted that it measured roughly 10cm across.

Evans believes the original team likely assumed the bone came from a marine reptile.

However, upon examining it, Evans immediately noticed features that strongly suggested it was dinosaurian. Given the 1985 discovery date, it would represent the earliest recorded dinosaur fossil found on the continent.

To verify his suspicions, he consulted Prof Paul Barrett from the Natural History Museum.

"It may not look particularly impressive at first glance, but it has a very distinctive structure," Barrett said while holding the fossil.

He highlighted a hollowed surface on one end before turning it over to show a rounded projection on the other. These shapes form ball-and-socket joints when linked together, allowing flexibility along the spine from head to tail.

"The moment I saw it, I recognised what it was — there was no doubt we were looking at a Titanosaur," he said. "The combination of characteristics is unique to this group of dinosaurs."

Today, more than 100 Titanosaur species have been identified worldwide.

All were four-legged herbivores with elongated necks that enabled them to browse high vegetation, along with long tails that balanced their massive bodies. The largest species could exceed 115ft (35m) in length and weigh around 60 tonnes.

Based on the dimensions of this vertebra, researchers estimate the Antarctic Titanosaur measured approximately 23ft (7m) long.

"It could have been a young individual, or perhaps it was simply a smaller species — one that differed from the typically gigantic members of its group," Barrett suggested.

This dinosaur lived around 82 million years ago during the Late Cretaceous Period, when Antarctica’s environment was dramatically different. Instead of ice, the continent was covered in dense forests that would have supported plant-eating giants like this one.

The once-forgotten fossil now occupies an important place in Antarctic exploration history. While additional dinosaur fossils have been found on the continent since 1985, they remain scarce.

Fieldwork in Antarctica is notoriously difficult, and thick ice sheets conceal much of the ancient rock that holds clues to prehistoric life.

"It demonstrates that a place we now consider extremely inhospitable was once thriving with life and home to a diverse array of species," Barrett explained.

"Discoveries like this help us understand how these animals were part of broader ecosystems at the southernmost reaches of the world roughly 80 million years ago."

A scientific paper detailing the discovery has been published in the journal Acta Palaeontologica Polonica.