The end of the Cretaceous Period, 66 million years ago, marked the dramatic extinction of the dinosaurs. Until now, our understanding of this mass extinction has been largely shaped by fossils from North America. However, a recent study led by Verónica Díez Díaz from the Museum für Naturkunde Berlin, identifying two new dinosaur species from Romania, highlights the crucial role of European fossil discoveries in providing a more comprehensive picture of this extinction episode.
The researchers report on two new sauropod species, Petrustitan hungaricus and Uriash kadici, found in the fossil-rich Hațeg Basin in western Romania. Their findings, published in the Journal of Systematic Palaeontology, reveal that the diversity of these long-necked plant-eating dinosaurs in Europe during the Late Cretaceous was far greater than previously thought.
Fifteen years ago, only five sauropod species were known from this time period. As of now, at least 11 have been identified—a stark contrast to North America, where only one sauropod species from the same epoch has been documented.
“The extraordinary diversity in a small geographic area like Hațeg Island is remarkable,” says Díez Díaz. “Here, sauropods of various sizes coexisted: from giants more than 10 meters long and weighing 8 tons to dwarfs just 2.5 meters in length and less than 1 ton in weight. This provides fascinating insights into the environmental conditions that allowed the coexistence of different species.”
Traditionally, it was believed that the dinosaurs of Hațeg Island adapted to their limited habitat by becoming smaller—a phenomenon known as “island dwarfism.” However, the discovery of the large sauropod Uriash challenges this assumption. “Local evolution was more complex than previously thought, showing that not all species reduced their size,” adds Zoltán Csiki-Sava from the University of Bucharest.
The study also highlights connections between European dinosaurs and their relatives in Africa, Asia, and South America. “Migrations facilitated by temporary land bridges or even swimming across seas more than 500 kilometers may have contributed to this diversity,” explains Paul Upchurch from University College London.
Philip Mannion, his institutional colleague and another co-author of the study, states, “Some of these dinosaurs were descendants of earlier faunas, while others arrived in the region only recently.”
Although this research has expanded our understanding of European titanosaurs, much remains to be discovered. “New fossil sites continually provide fresh material that helps us better understand the past,” emphasizes Díez Díaz. The team is confident that Europe’s fossil discoveries will continue to revolutionize our understanding of the Cretaceous Period.
More information: Verónica Díez Díaz et al, Revision of Romanian sauropod dinosaurs reveals high titanosaur diversity and body-size disparity on the latest Cretaceous Haţeg Island, with implications for titanosaurian biogeography, Journal of Systematic Palaeontology (2025). DOI: 10.1080/14772019.2024.2441516
Journal information: Journal of Systematic Palaeontology
Provided by Museum für Naturkunde – Leibniz-Institut für Evolutions- und Biodiversitätsforschung