84-Million-Year-Old Horned-Dinosaur Fossils Rewrite Europe’s Prehistoric Record
Horned dinosaurs lived in Europe during the late Cretaceous, although they are considered largely absent from the continent’s fossil record. A new study published in Nature shows that several European dinosaurs long classified as other herbivores – including a species called Ajkaceratops – are actually ceratopsians, the group that includes Triceratops.
The reclassified fossils date from around 84 million years ago, when Europe was just a chain of islands along the Tethys Sea. The study also reveals that some dinosaurs previously assigned to a European-only group known as rhabdodontids were misidentified, which explains why ceratopsians appear to have disappeared from the continent for so long.
“Although Iguanodon and Triceratops look very different, the groups they are part of both evolved from a common ancestor, meaning they both inherited certain characteristics,” lead author Susannah Maidment said in a press release. “They also independently evolved four legs, complex chewing mechanisms, and large body size. This means that their teeth and limbs look very similar, both because of their shared history and their lifestyle. So when we only have small parts of the skeleton to look at, it can be quite difficult to tell what it is.”
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New fossils redefine Ajkaceratops
Using recently recovered cranial material from Ajkaceratops, along with CT scans and multiple analyzes of evolutionary relationships, the researchers were able to more confidently place the species in the ceratopsian family tree.
This work also revealed that a dinosaur previously described as a separate species, Mochlodon, turned out to be the same animal as Ajkaceratops. Beyond that, analyzes showed that several other European dinosaurs long considered rhabdodontids – a group considered unique on the continent – also belonged to Ceratopsia.
“The first discovered fossils of Ajkaceratops were so incomplete that many scientists doubted whether it was a ceratopsian. What’s so exciting about the new Ajkaceratops fossil is that it allows us to confirm that horned dinosaurs roamed the European Cretaceous islands, but also challenges us to radically rethink our understanding of these ancient ecosystems,” said paper co-author, Richard Butler, in a press release.
European island geography shaped ceratopsian migration
At the end of the Cretaceous, Europe was very different from today. Rising sea levels have divided the continent into a mosaic of islands separated by shallow seas, creating ecosystems shaped by isolation and intermittent connections with other landmasses.
This geography may help explain why European ceratopsians remained smaller and harder to recognize than their later relatives in North America. It also puts Europe in a more central role in studying how ceratopsians moved and evolved in the Northern Hemisphere.
The group’s earliest members, like Yinlong, evolved in Asia before expanding outward. From there, ceratopsians dispersed several times across North America, where they eventually gave rise to large, frilled species like Triceratops. Europe lies between these regions – a position that makes it a plausible travel route, although direct fossil evidence has long been difficult to identify.
“We know that dinosaurs were able to cross the Atlantic, which was just beginning to open up in the Cretaceous,” Maidment said. “Dinosaurs such as Allosaurus have been discovered in Portugal and the United States, showing that they had at least some ability to move between continents. Many animals can swim, and since the islands of the Central European Basin were not that far apart, it would make sense that dinosaurs were able to jump from one island to another.”
Reframing the European dinosaur record
Europa now appears to have been part of the larger ceratopsian world, although its fossils were harder to recognize due to anatomical overlaps with other herbivorous dinosaurs.
“Horned dinosaurs like Triceratops are some of the most iconic dinosaurs, but most of them came from North America, and now we’ve found them in Europe, hidden in plain sight because they were misidentified for decades as other types of dinosaurs,” said co-author Steve Brusatte.
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