The first confirmed dinosaur remains discovered in Antarctica have been identified as belonging to a sauropod, more than four decades after initially being mistaken for a marine reptile. The fossil was originally found in 1985 on James Ross Island, located on the southeastern side of the Antarctic Peninsula, during a British Antarctic Survey (BAS) expedition led by Dr. Mike Thomson.

At the time, researchers were primarily searching for invertebrate fossils, such as ammonites, and the fragmentary bone was overlooked, likely due to challenging field conditions and its presence in marine sediment. The fossil was embedded in rock from the Late Cretaceous period, approximately 82 million years ago, when the region supported lush forest ecosystems. Scientists now believe the specimen represents the earliest dinosaur remains collected on the continent, which features a notably sparse dinosaur fossil record largely due to extensive ice coverage.

Researchers from the Natural History Museum confirmed the sauropod identification after reexamining the fossil. Professor Paul Barrett noted the initial misidentification, while Dr. Mark Evans of BAS highlighted that Thomson had suspected the find was from a large reptile. The bone’s preservation in marine deposits suggests the animal likely floated out to sea post-mortem before becoming fossilized on the ocean floor.

Though incomplete, the fossil appears to belong to the titanosaur group within the broader sauropod family. Titanosaurs were among the largest dinosaurs, distinguished by their long necks and herbivorous diets. Members of this group often weighed more than 15 tonnes and could reach neck lengths of up to 39 feet. However, the 1985 specimen measured only six to seven meters, indicating it may have been either a juvenile or a dwarf species.

Antarctic dinosaur fossils have so far been found mainly in two areas: the Transantarctic Mountain range and the Antarctic Peninsula. These sites provide exposed rock formations along shorelines, while much of the continent’s fossil record remains hidden beneath thick ice. Scientists have suggested that ongoing climate change and the associated retreat of ice could reveal additional fossil evidence, offering further insight into past biodiversity.

This discovery also contributes to understanding the biogeography of titanosaurs and their migration routes across southern continents. Findings suggest these dinosaurs likely used the Antarctic Peninsula as a corridor to move between South America and New Zealand, bypassing Australia. To date, about six dinosaur species have been identified from Antarctic fossils, although experts believe the actual diversity that once inhabited the region was considerably greater.