This week we will be checking out a unique dinosaur that lived in an even more unique environment. Let's talk about Ajkaceratops kozmai!
Ajkaceratops was a small plant-eating dinosaur that lived in what is now Hungary during the late Cretaceous period, about 85 million years ago. From beak to tail it likely measured a little over 3 feet (1m) long. The genus name translates to "Ajka Horned Face", referencing the town in Hungary near where its fossils were found.
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| Watercolor of Ajkaceratops by Christopher DiPiazza. |
Ajkaceratops was initially published in 2010 from the front of the beak. The beak itself was curved and pointed, much like a ceratopsian, the "horned dinosaurs", like Triceratops, so it was placed in that family alongside dinosaurs like Protoceratops. Later on, the beak was re-examined and many unique traits were noted about it compared to other ceratopsians, like the fact that it has a more rounded cross-section and its pitted texture. It also appears to be completely fused to the rest of the jaw, which is only seen in mature members of the larger members of the ceratopsian group, like Triceratops. Based on this it was deemed not a ceratopsian at all, but rather an unusual kind of ornithithopod dinosaur, related to Zalmoxes, which was also found in Europe. Then most recently more fossils from Ajkaceratops were found, including a more complete skull, and in 2026 they were published on. Based on this new material it was found to be a ceratopsian after all. Not only that but a few members of the ornithopod group it was previously grouped with, called the rhabdodontids, were also thought to be unusual ceratopsians as well. This is an important determination since prior to this, ceratopsians were only ever found in North America and Asia, and it was odd that they wouldn't be in Europe. Ajkaceratops proves they were.
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| Ajkaceratops' skull. Image from the most recent paper by Czepinski et al. referenced below. |
It's not surprising the identity of Ajkaceratops was not clear since it is indeed unusual for a ceratopsian. As mentioned, it beak is extremely long, narrow, and curved, even for a ceratopsian, which are known for having curved beaks. In fact, its whole skull is pretty elongated, and almost rectangular in profile. As mentioned, the beak was completely fused to the rest of the jaw, and not a separate bone as it is in vast majority of other ceratopsians, called a rostral bone. Lastly its extremely small size is also unusual especially for living in the late Cretaceous. The teeth were more typical and appear to be ideal for shredding plants. They show a high amount of wear on them, suggesting Ajkaceratops could have been regularly chomping through tougher plant material like twigs and pine needles.
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| Teeth of Ajkaceratops. Image from paper by Osi et at. referenced below. |
The part of Hungary that Ajkaceratops was found in was actually an island when it was alive. That part of Europe was known to be a series of island chains during that time, and paleontologists think the ancestors of Ajkaceratops may have actually have swam there from either Asia or North America. (since ceratopsians were living on both those continents already before Ajkaceratops' time)
References
Czepiński, Łukasz; Madzia, Daniel (2024). "Osteology, phylogenetic affinities, and palaeobiogeographic significance of the bizarre ornithischian dinosaur Ajkaceratops kozmai from the Late Cretaceous European archipelago". Zoological Journal. 202 (4).
Ősi, Attila; Butler, R.J.; Weishampel, David B. (2010-05-27). "A Late Cretaceous ceratopsian dinosaur from Europe with Asian affinities". Nature. 465 (7297): 466–468.
Maidment, Susannah C. R.; Butler, Richard J.; Brusatte, Stephen L.; Meade, Luke E.; Augustin, Felix J.; Csiki-Sava, Zoltán; Ősi, Attila (2026-01-07). "A hidden diversity of ceratopsian dinosaurs in Late Cretaceous Europe". Nature: 1–7.
