Dinosaur fossils pertaining to the Rhabdodontidae family, unique in the world, with an aproximated age of 70 million years, have been discovered on the site of the International UNESCO Geopark Țara Hațegului, administered by the University of Bucharest, in the proximity of Vălioara in the Hațeg Basin, located in the Hunedoara County. The finding is the accomplishment of an international research team comprising researchers from the Faculty of Geology and Geophysics of the University of Bucharest and the Paleontology Department of the “Eötvös Loránd” Tudományegyetem University in Budapest (ELTE – „Eötvös Loránd” Tudományegyetem). The first indications of existing fossil sites in the area were identified in 2019, and further research has brought to light the remains of a rich association of vertebrates that lived here towards the end of the Cretaceous Period.
Most of the dinosaur fossils uncovered belong to a herbivorous species, biped and mid-length, 2-6 meters long, member of the Rhabdodontidae group. The study of this rich fossil material is continuing owing to a multiannual collaboration agreement between the two universities, and the first results of this research were published in December 2023 in the Cretaceous Research magazine, which confirms the discovery within the scientific community. The bones discovered are very well preserved, they have no fissures and have not been deteriorated excessively despite their age, and they include parts of the skeleton that have never been identified in Rhabdodontidae prior to this study.
Although relatives of these dinosaurs where found on other continents as well, for instance in North America or even Australia, the Rhabdodontidae family itself has been strictly endemic to inland Europe 85 to 66 million years ago. This group of herbivore dinosaurs, relatively small in size, of 2 up to 6 meters, presently include 9 different species, among which 3 exclusively from Transilvania, in Romania. In addition, many of these species have only been identified recently, in the last two decades, mainly due to the extension of systematic research, in the Hațeg Basin and other parts of Europe. The partial skeletons uncovered and studied by our team indicate, however, that this group of dinosaurs was probably much more diverse than we actually know, with new species which could be described in the future, affirmed the main author of the study and doctoral student at the “Eötvös Loránd” Tudományegyetem University in Budapest, János Magyar.
The fossil site named K2, the place of origin of the fossil association discussed in the recently published article, is situated in the westernmost part of the Hațeg Basin, where, according to our estimations, we can find the oldest sedimentary rocks containing reptile fossils, with an approximated age of 71 million years. Considering the different environments indicated by the rocks in Vălioara, as well as the somewhat older age, it is very likely that our discoveries unravel a new fauna association, undocumented in previous research. However, in order to confirm this, research has to be continued, declared the leader of the research team, PhD Gábor Botfalvai from the ELTE University.
The scientific significance of the material recovered from fossil site K2 is even greater because it contains the associated rests of a small number of individuals, probably just 2 or 3 belonging to the same species, individuals of similar sizes; the fossils preserved from these individuals included cranial elements as well as vertebras and limb bones. Such associations of skeleton elements representing different parts of the body – which thus allow an accurate reconstruction of the animal’s morphology – are extremely rare in the case of Rhabdodontidae, and the one studied by us is the first one strongly documented in the area around Vălioara, mentioned one of the coordinators of the research group, Zoltán Csiki-Sava, PhD, associate professor at the Faculty of Geology and Geophysics of the University of Bucharest.
The Hațeg Basin has been renowned, for more than a century, for the dwarf dinosaur fossil discoveries from upper Cretaceous formations. The first dinosaur remains uncovered in Hațeg were studied by the eccentric paleontologist Franz Nopcsa who, 120 years ago, described the first Rhabdodontidae remains. The dinosaur fossils in Upper Cretaceous in Europe are much rarer than those in deposits of the same age in North-America or Asia; in addition, these are usually less complete, fragmented and isolated. Thus, there is no known complete Rhabdodontid skeleton in the scientific community, which makes it very difficult to study the group systematically. The researchers in the international team consider that, by comparing the abundant Rhabdodontidae material described in the new study with the one already present in historical collections, as well as the in-depth analysis of the recently discovered fossils – or which are to be discovered in the near future -, will allow a much more detailed knowledge of this group of European dwarf dinosaurs, thus contributing to the understanding of their origin, specific diversity and evolution. At the same time, the study of fossil vertebrates recently uncovered in the Vălioara region will allow the contouring of a much more accurate image about the composition and fauna of dwarf dinosaurs that lived just a short-while before the extinction of the dinosaurs 66 million years ago.