A Fossil From Antarctica Sat in a Drawer for 40 Years. It Turned Out to Be the First Dinosaur Bone Ever Found on the Continent
After being forgotten for decades, the mysterious tail vertebra has finally been identified as part of a titanosaur. The discovery helps researchers understand how dinosaurs may have traversed Earth’s southernmost regions
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The biggest scientific breakthroughs can come from the most mundane places. A forgotten fossil that sat in a collection drawer for around 40 years is now providing a rare glimpse at the dinosaurs that roamed what is now Antarctica—and which paths they may have traveled around the south.
The specimen, an 82-million-year-old fossilized tail vertebra, marks the first dinosaur fossil ever recovered from the southernmost continent, scientists report in a study published on June 29 in the journal Acta Palaeontologica Polonica. It belonged to a titanosaur—a member of a group that included the largest dinosaurs known to walk the Earth.
Geologist Mike Thomson collected the fossil in December 1985. He and other members of the British Antarctic Survey (BAS) were conducting an expedition to map rock layers on James Ross Island. At the time, Thomson thought that the vertebra came from an ancient marine creature, like the other fossils found by the team. So, the unassuming bone was boxed up, transported back to the U.K. and left unstudied in a storage drawer.
Its true identity came to light when study co-author Mark Evans, a paleontologist and collections manager at BAS, was sorting through the archive. He suspected that the uniquely shaped tail bone belonged to a dinosaur, so he contacted Paul Barrett, a paleontologist at the Natural History Museum in London.
“As soon as I saw it, I knew what we were dealing with … It was a dead cert we were dealing with a titanosaur,” Barrett, who also co-authored the research, tells BBC News’ Alison Francis. Some of the ten-centimeter-long bone’s distinguishing features include a hollow on one end and a round bump on the other, revealing how it fit in with other vertebrae in a line of ball-and-joint sockets. “This is a combination of features that’s completely unique to these types of dinosaurs,” Barrett notes.
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Scientists have identified about 100 species of titanosaur. They were four-legged, long-necked plant-eaters that balanced their immense frames with heavy, sweeping tails. The largest known of these lumbering giants, Patagotitan mayorum, is thought to have stretched a staggering 122 feet and weighed approximately 77 U.S. tons.
The newly identified Antarctic dinosaur fossil is too incomplete to know what species it belonged to. However, the team’s analysis suggests the creature was relatively petite at an estimated 23 feet long.
“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 tells BBC News. Since it was found in a marine rock formation, he and his colleagues suspect that after the animal died, it likely floated out to sea before sinking to the seafloor to fossilize alongside other animals, like ammonites. Their remains helped the team determine the surrounding rock’s age.
Quick fact: Other dinosaur bones found on Antarctica
Since 1985, researchers have found additional dinosaur specimens on the southernmost continent. They have identified 12 species from there and have recovered bones whose species remain unknown, the authors write in the paper.
The discovery is extra special because it helps explain a fragmentary fossil record in today’s southern landmasses. No titanosaur fossils have been identified in Australia, and a few have been recovered from New Zealand. South America, on the other hand, is teeming with them.
During the late Cretaceous, about 66 million to 100.5 million years ago, these regions were loosely connected remnants of the southern supercontinent Gondwana. “At the time, New Zealand was, weirdly, quite a long way away from Australia,” Barrett says in a statement from the Natural History Museum. “It was closer to southern South America and the Antarctic Peninsula than it was to Australia, just because of the way the continents have moved around.”
This prehistoric layout, along with the vertebra, suggests that the Antarctic Peninsula may have served as a vital land bridge, allowing these massive dinosaurs to march between South America and New Zealand, all while skipping Australia. Despite being at the South Pole, Gondwana was warm at that time, thanks to intense volcanic activity that pumped heat-trapping carbon dioxide into the atmosphere.
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What’s more, the newly described fossil serves as an important reminder that stowed museum specimens have the power to unravel the mysteries of the past.
“This bone sat in a collection drawer for decades until new research revealed it for what it was,” says study co-author Matt Lamanna, a palaeontologist at the Carnegie Museum of Natural History, in a statement from University College London. “It’s a powerful reminder of exactly why museums collect, care for and steward objects like these—new methods and expertise continue to emerge, enabling scientists to unlock discoveries from specimens that have been waiting in plain sight.”