Antarctica’s first dinosaur bone was overlooked for decades

The first dinosaur bone ever collected in Antarctica is not the one the record books name. For decades that honor went to an armored dinosaur found in 1986 on James Ross Island, off the tip of the Antarctic Peninsula. But a year earlier, on December 9, 1985, two geologists working on the same island had already picked up a piece of a dinosaur. Nobody realized it.

Their find was a single tail bone from a titanosaur, one of the long-necked, plant-eating sauropods that include the largest animals ever to walk on land. Paleontologist Paul Barrett of the Natural History Museum in London and seven colleagues described it in June 2026 in the journal Acta Palaeontologica Polonica. That makes it Antarctica’s first dinosaur bone, in the order of collection, and only the second sauropod bone known from the whole continent. Michael Thomson of the British Antarctic Survey and Reinhard Förster of the Bavarian State Collection for Palaeontology and Geology in Munich brought it back, and it went into the survey’s collections as specimen BAS D.8621.25. Until this study, it had never been mentioned in print.

Antarctica is a hard place to hunt dinosaurs. It has the sparsest dinosaur record of any continent, the authors note. Almost everything comes from two places: Early Jurassic rocks in the Transantarctic Mountains, and Late Cretaceous rocks on a cluster of islands next to the Antarctic Peninsula, James Ross Island among them. From those islands, scientists have reported armored ankylosaurs, plant-eating ornithopods, meat-eating theropods and early birds. Sauropods are the rarity.

How a single tail bone points to a titanosaur

One end is a cup, the other a ball. The fossil is a vertebra from the front part of the tail. Its front face is a shallow hollow, and its back end swells into a smooth, rounded knob. In life, each tail bone slotted into the next a bit like your shoulder sits in its socket. Paleontologists call this shape “procoelous.” Among sauropods, a strong version of it shows up mainly in an advanced branch of titanosaurs called lithostrotians.

The scanner saw through a disguise. The team ran the vertebra through a computed tomography (CT) scanner at the Natural History Museum, the same X-ray method hospitals use to see inside the body, and also made a 3D surface scan. Some titanosaurs, such as the saltasaurines of South America, had bones riddled with small air chambers. From the outside, this bone seemed to have them too. The scans showed it didn’t. Those “chambers” were eroded patches of gravelly rock and small pebbles stuck to the surface. Inside, the bone was a tight mesh of bony struts with no air spaces at all, which rules out the saltasaurines.

Its closest look-alike is from Argentina. The forward lean at the base of the bone’s upper arch, and the centered ball at the back, best match a tail bone from Patagonia once assigned to Muyelensaurus pecheni, a Late Cretaceous titanosaur, and more recently reassigned to a related group, the aeolosaurines. It also resembles Rinconsaurus caudamirus and Aeolosaurus rionegrinus. Here’s the catch: those groups are hard to tell apart, and the titanosaur family tree is still being redrawn. So the authors played it safe. They classed the animal as a eutitanosaur, a member of the large, late-branching group of titanosaurs, and named no genus or species.

This titanosaur was a small one. The vertebra is about 60% the size of the matching bone in Baurutitan britoi, a titanosaur from Brazil, and about 75% the size of the one in Neuquensaurus australis, which is already counted as a dwarf. It matches the size of the same bone in Magyarosaurus dacus, a famously small titanosaur from an ancient island in what is now Romania. The bone’s body and its arch are fused, and that usually signals an adult. In sauropods, though, fusion doesn’t follow a fixed schedule. The authors conclude that the animal was either a youngster or a genuinely small adult.

What dinosaurs lived in Antarctica, and in what climate

The older sauropod record got turned on its side. Until now, the only direct evidence of sauropods in Antarctica was a partial tail bone from a younger rock layer on the same island, reported in 2012 by Cerda and colleagues in the journal Naturwissenschaften. Barrett’s team took a second look and argues it was pictured in the wrong orientation: what was shown as the side of the bone is really the underside of half a vertebra. They agree it belongs to the same broad group of titanosaurs, but it’s too damaged to say much more.

The bone turned up among sea creatures. The rock it came from, the Santa Marta Formation, formed in a deep-water delta. It’s full of ammonites, coiled shellfish related to squid, along with clams and fossil wood, and the vertebra lay next to fish scales and plant fossils. Animals with four limbs are rare there: a sea turtle shell, a pterosaur hand bone, a few plesiosaurs. This bone is the only dinosaur ever found in the formation. A strontium isotope date from a matching layer nearby puts it at about 82.6 million years old, early in the stretch of the Cretaceous called the Campanian.

The climate was mild, not polar. Antarctica was not cold during the dinosaurs, at least not here. Fossil leaves of flowering plants from a slightly older part of the same formation point to an average yearly temperature of about 66 degrees Fahrenheit (19 degrees Celsius), with rainfall similar to a modern tropical rainforest and no serious winter frost, even at a high latitude. The authors think the dinosaurs lived on the land of a nearby chain of volcanoes, where those plants grew. Honestly, it’s hard to picture a long-necked plant eater browsing a warm, wet forest on ground that today is bare, wind-scoured gravel. It fits a growing sense that the Cretaceous world ran warmer than the old picture, from polar forests to how warm T. rex itself ran.

Why dinosaur fossils from Antarctica are so rare

Sauropods were barely hanging on. Climate models from a 2022 study in Current Biology, co-written by Philip Mannion of University College London, one of the new paper’s authors, suggest that parts of northern Antarctica worked as corridors for sauropods. Only just, though. In those models, the habitat there was marginal for sauropods and better for theropods and ornithischians, the group that includes armored and duck-billed dinosaurs. That fits what fossil hunters have found so far in the region: far more of those other dinosaurs than long necks.

Antarctica was the crossing point. Titanosaurs and their close relatives are common in the Cretaceous rocks of South America and Australia, and one turns up in New Zealand too. Their ancestors must have passed through Antarctica at some point, the authors write. Australia’s known sauropods from that time belong to a different branch, the diamantinasaurians, which sit at or just below the base of the titanosaur tree. The new bone isn’t one of them. So at least two lines of these sauropods lived in Antarctica, though not necessarily at the same time. A tail bone from New Zealand of roughly the same age is probably a eutitanosaur, too, and the Antarctic Peninsula looks like the likeliest route from South America toward Zealandia, the mostly sunken continent New Zealand sits on.

One bone can only say so much. The authors stress that the vertebra is fragmentary, which is why they stop short of naming a species. Its small size could mean a juvenile or a small-bodied adult, and the bone alone can’t settle which. The gaps in the record cut deeper. Antarctica has no mid-Cretaceous dinosaur fossils and Australia has no Late Cretaceous ones, so the team can’t tell whether the two sauropod lines ever shared the same ground. And the habitat models describe what conditions allowed, not where animals actually lived.

The next find may already be in storage. The CT and surface scans are free to view on MorphoSource, an online archive of 3D specimens, so other researchers can check the comparisons for themselves. Thomson and Förster’s field season also brought home other reptile fossils from the same islands, finds that led the Natural History Museum to send a vertebrate paleontologist on a later expedition. A bone that waited about four decades to be recognized is a fair hint that Antarctica’s next dinosaur might come out of a collection cabinet rather than out of the rock.

Source: Barrett, P. M., Mannion, P. D., Beeston, S. L., Lamanna, M. C., Clark, B., Otero, A., O’Gorman, J. P., and Evans, M. “A titanosaurian sauropod dinosaur from the Late Cretaceous of Antarctica.” Acta Palaeontologica Polonica 71(2): 349-362 (2026). DOI: 10.4202/app.01315.2025

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