Hungarian paleontologists have discovered a new herbivorous, duck-billed dinosaur in the Hațeg Basin. Because associated skeletons - connected remains from the same individual—are extremely rare in the region, it took the researchers several years to identify the new species. The discovery highlighted that the unique fauna of the “Hațeg Island” may have been far more diverse than experts had previously thought.

Researchers from ELTE University, the Hungarian Museum of Natural History, the Supervisory Authority for Regulated Activities (SARA) and the University of Bucharest have been conducting excavations near the village of Valioara in the Hateg Basin in Southern Transylvania since 2019. During the excavations, thousands of fossils from the late Cretaceous period, dating back to 70 million years ago, have been collected from the site. The dinosaur remains that are frequently found during the excavations belong to the Ornithischia group, including the remains of the herbivorous Hadrosauroid - or duck-billed dinosaur - that have been recognized as a new species.

“The site where the new species comes from was found in 2022, thanks to a newly constructed road. This happened when we were conducting geological mapping in the areas north of Valioara in the hope of finding new layers of rock containing vertebrate fossils. Thanks to the road cut into the hillside, the dark gray sand layers that we knew as bone-containing layers found in other sites we had previously discovered in the Hateg Basin came to the surface. During the excavations at the new site, we found not only individual bones, but also a complete partial skeleton of a Hadrosauroid dinosaur,” summarized the story of the discovery of the site by Dr. Gábor Botfalvai, assistant professor at the Department of Paleontology at ELTE and leader of the research team. 

Excavation at the new site. Photo: Valiora Dinosaur Research Group (VDRG).

Remains of hadrosauroid dinosaurs were already known from Transylvanian sites, most of which were routinely classified as the species Telmatosaurus transsylvanicus, which was discovered more than 130 years ago. 

“Comprehensive skeletons that include cranial elements, vertebrae and limb bones are very rare in the Hateg Basin, and this is especially true for Hadrosauroid remains. Most sites usually only contain isolated bone elements from this dinosaur group, which, although often lacking defining features, was generally thought to belong to the previously known Telmatosaurus. Therefore, Telmatosaurus and its remains had to be redefined in order to be able to compare the newly discovered skeleton with it in detail,” said Dr. Attila Ősi, head of the Department of Paleontology at ELTE and one of the co-authors of the study.

Reconstruction of the skull and skeleton of Kryptohadros kallaiae. The skeletal elements marked in gray were found during the excavation. Source: János Magyar.

As it turned out, this Valioaran skeleton belongs to a completely new dinosaur species, named Kryptohadros kallaiae, which existed somewhat (up to 1-2 million years) earlier than Telmatosaurus. The “Kryptohadros” in the newly introduced name refers to the fact that for almost 130 years only one hadrosauroid species was known from Transylvania, and this second one remained “hidden” in the shadow of Telmatosaurus; while the name “kallaiae” is honor for Csilla Kállai, the mother of the first author of the publication, who passed away early and who always encouraged her son in his interest in natural sciences.

"The similarity between the new species and Telmatosaurus, is quite high, because they are close relatives. The differences are mostly visible only in the morphology of the skull elements. Another important result of our research is that, based on our phylogenetic studies, the closest relative of Kryptohadros is Tethyshadros found in Northern Italy, with which the three mentioned species together represent a separate evolutionary branch of Asian origin, but characteristic of Southeast Europe," said János Magyar, a doctoral student at the Department of Paleontology at ELTE and a colleague at the Hungarian Natural History Museum, and the first author of the publication published in the Journal of Systematic Palaeontology.

“Based on the phylogenetic tree of the study, it seems that Hadrosauroid dinosaurs that evolved in Asia reached Africa and North America through Europe in at least 7 separate migration events, one of which resulted in the common ancestor of Kryptohadros and its relatives reaching the southeastern part of Europe. We would like to investigate this suggestion further in the future. But the current result already confirms that the fauna of the European archipelago that existed at this time changed dynamically,” added Dr. Zoltán Csiki-Sava, associate professor at the University of Bucharest and leader of the romanian part of the research group. 

Kryptohadros and its immediate relatives represent a separate clade, which was named Telmatosauridae. It is marked in red in the image. Source: Magyar János.

With the discovery of this new species, another piece of the unique fauna of the so-called “Hateg Island” that existed at the very end of the Cretaceous period has become known. This fauna may therefore have been much more diverse than researchers previously thought.
 

(Cover picture: Body reconstruction of Kryptohadros. Source: Tibor Pecsics.)