In 1985, British Antarctic Survey geologist Mike Thomson picked up a vertebra on James Ross Island and recorded it as the remains of a large reptile. The specimen then spent decades in a geological collection.

In 2026, modern analysis finally established what it was: a tail vertebra from a titanosaurian sauropod. That identification made specimen BASD8621.25 the first dinosaur fossil ever collected on the Antarctic continent.

A dinosaur fossil found before Antarctica’s dinosaurs were known

The timing is what makes the specimen remarkable. It was collected before the first Antarctic dinosaur discoveries were formally recognized. The bone was already sitting in a collection while the scientific picture of Antarctic dinosaurs was still developing.

What CT scanning added

Researchers used CT scanning and anatomical comparisons to examine the internal and external structure of the vertebra. The features pointed toward a eutitanosaurian sauropod, part of the wider group of long-necked dinosaurs that included some of the largest land animals ever known.

This animal, however, may have been relatively small. Estimates discussed by the research team put it at roughly six to seven metres long. Whether that reflects a genuinely small-bodied species or a juvenile individual remains uncertain.

Why was a land dinosaur in marine rock?

The vertebra came from marine deposits of the Santa Marta Formation, dating to the Late Cretaceous. That does not mean the dinosaur lived at sea. A carcass or bone could have been transported from land before being buried in marine sediment.

Antarctica was not always an ice world

During the Cretaceous, Antarctica was connected within a very different southern geography and supported ecosystems capable of sustaining dinosaurs. The new identification adds another piece to discussions about dinosaur dispersal between Antarctica and South America.

The larger lesson is equally useful: museum and geological collections are not static archives. New imaging methods and new comparative material can turn an overlooked specimen into a significant discovery decades after it was collected.

Sources

• British Antarctic Survey — Antarctica’s first dinosaur fossil confirmed
• Research paper — A titanosaurian sauropod dinosaur from the Late Cretaceous of Antarctica

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