Dr Mike Thomson’s 1985 geological field notebook next to the dinosaur fossil vertebra found in Antarctica. Credit: British Antarctic Survey
A fossil collected on James Ross Island in 1985, then stored for decades in a British Antarctic Survey geological collection, has now been formally identified as the first dinosaur bone ever found on the Antarctic continent.
The fragment belonged to a titanosaur, a long-necked plant-eater from a group that included the largest animals ever to walk on land. The discovery shows that titanosaurs once lived in Antarctica, at a time when the continent was warmer, greener and still linked to other southern landmasses.
Vertebra of a Large Reptile
The fossil isn’t complete enough to reveal which dinosaur species it came from, but it’s definitely a titanosaur. Credit: Barrett at al. 2026
Dr. Mike Thomson was not searching for dinosaurs at all. His 1985 expedition aimed to map rock layers on James Ross Island, near the Antarctic Peninsula, so later geologists and paleontologists could date fossils found in the region.
In his field notebook, he sketched the fossil and called it a “vertebra of large reptile,” noting that it was about 10 centimeters wide.
The bone was stored in the British Antarctic Survey’s (BAS) geological collection in Cambridge. For decades, it was thought to be from a marine reptile, a reasonable assumption since it came from marine rocks.
Fast-forward to today when Dr. Mark Evans, a paleontologist and collections manager at BAS, spotted it among thousands of Antarctic specimens.
“This fossil was found by Dr Mike Thomson, one of the true pioneers of Antarctic geology,” said Evans, a paleontologist and manager of the geological collections and labs at the British Antarctic Survey. “When I first spotted this bone in our collections a few years ago, I suspected it was a dinosaur. After looking at it properly, I thought it was probably a titanosaur tail vertebra. 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.”
“As soon as I saw it, I knew what we were dealing with… it was a dead cert we were dealing with a Titanosaur,” Professor Paul Barrett, a sauropod expert at the Natural History Museum in London, told the BBC. “This is a combination of features that’s completely unique to these types of dinosaurs.”
×
Thank you! One more thing…
Please check your inbox and confirm your subscription.
Small Giant
Artistic reconstruction of the small sauropod. Credit: Andrew McAfee, Carnegie Museum of Natural History
Titanosaurs were sauropods: four-legged herbivores with long necks, long tails, and massive bodies. Some reached more than 35 meters in length and weighed around 60 tons.
This Antarctic animal was far smaller. Researchers estimate it was about six to seven meters long. The fossil cannot show whether it was a juvenile or a smaller adult.
“Maybe it was a juvenile dinosaur, or maybe it was a genuinely small one—one that was actually bucking the trend for the rest of the group as a smaller adult,” Barrett added.
The official paper identifies the fossil as a small anterior caudal vertebra—a front tail bone. The authors classify it cautiously as an indeterminate eutitanosaurian, a more derived titanosaur, because the specimen is too incomplete to name a species. Its anatomy resembles some South American titanosaurs, including material linked to Muyelensaurus pecheni.
The rock around the fossil gives scientists a firmer answer on its age. It came from the Santa Marta Formation, a marine rock layer from the Late Cretaceous, about 82 million years ago.
“It’s quite precisely dated because it’s from marine rocks,” Barrett told the Natural History Museum. “The vertebra was found alongside bits of ammonite, and so this is an animal that would have floated out to sea after it died, perhaps washed out by a river.”
At the time, Antarctica was not the frozen continent people know today. The Antarctic Peninsula was still connected to southern South America. Forests of ferns, palms, and conifers covered the region. Animals and plants at these high latitudes would have lived with extreme seasonal shifts in daylight.
The Dinosaur Spread
The fossil was collected by Mike Thomson, pictured, during a 1985 expedition to James Ross Island. Credit: British Antarctic Survey
Since 1985, researchers have described only a small number of dinosaur fossils from Antarctica, including armored ankylosaurs, small herbivores, carnivorous theropods and ancient birds. Sauropods remain especially rare: this newly identified bone is only the second sauropod body fossil known from the continent. Unlike other continents, Antarctica’s environment is simply too brutal for efficient field work so progress will remain painfully slow. Most of Antarctica’s fossils will remain locked under ice for the foreseeable future.
“Believe it or not, this is the first bit of dinosaur ever discovered on Antarctica,” Barrett noted. “It was overlooked because I think it was misidentified while under harsh field conditions, but it is a sauropod and it’s only the second sauropod bone from the entire continent.”
The fossil may also help explain how titanosaurs spread through the southern continents when Antarctica, South America and Zealandia were closer together. Titanosaur fossils showed up in South America and New Zealand, but not yet in Australia.
The study was published in the journal Acta Palaeontologica Polonica.