70 million years before it became famous for its vampires, Transylvania was part of a large subtropical island known as Hațeg (pronounced like “hots egg”). Its unique fauna provides a window into island life at the end of the Age of Reptiles. Its rocks are exposed in western Romania and date from the Maastrichtian, the final age of the Late Cretaceous, approximately 70 million years ago. Hațeg was one of several large islands that existed in Europe at the time.
During the Late Cretaceous, much of Europe was made up of large low-lying islands in a shallow sea, like a mix of Indonesia and The Bahamas. Hațeg Island was a large island, roughly the same size as Hokkaido or Ireland. It existed during the final 20 million years of the Mesozoic.
Most fossiliferous deposits from the island were formed in the early part of the Maastrichtian Age, roughly 70 million years ago. They show that the island’s lowlands were dominated by braided river systems and dry flood plains. Hațeg was subtropical with distinct rainy and dry seasons and open broadleaf forests.
Hațeg Island, and other islands of the European Cretaceous, are notable for their dinosaur fauna with numerous examples of dwarfed lineages. Island dwarfism, like that seen in the Hațeg dinosaurs, is often a result of limited food resources.
The pterosaurs of Hațeg were the top predators of the island. The pterosaurs are all azhdarchids, and include the giant Hatzegopteryx thambema, the medium-sized Eurazhdarcho langendorfensis, and a third unnamed medium-sized species. Azhdarchids were predators of terrestrial vertebrates including dinosaurs. The pterosaurs of Hațeg are the largest predators known from the island, much larger than any carnivorous dinosaurs discovered there.
Hațeg Island has two known sauropod species, Magyarosaurus dacus and Paludititan nalatzensis. Both species are titanosaurs, but far from being titanic, they are among the most dramatic examples of island dwarfism. They were both about 6-8 meters in length and weighed only about one tonne.
Throughout the age of dinosaurs, most medium- and large-sized terrestrial predators were theropod dinosaurs. Hațeg Island was unusual in that all known theropods were small. They include the possible alvarezsaurs Heptasteornis andrewsi and Bradycneme draculae, and the possible troodontid Elopteryx nopscai. All three taxa are based on fragments, so their assignment to specific families is tentative. Balaur bondoc is known from more complete remains which appeared to have two raised sickle-claws on each foot. Initially considered an unusual dromaeosaur, subsequent research suggests Balaur was a large herbivorous bird that used its unusual foot claws to perch.
Several small- to medium-sized bird-hipped dinosaurs are known from Hațeg. They include the small armored nodosaurid Struthiosaurus transylvanicus, the emu-sized rhabdodontids Zalmoxes robustus and Z. shqiperorum, and the small duck-billed hadrosaur Telmatosaurus transsylvanicus. Both Struthiosaurus and Telmatosaurus were substantially smaller than their mainland relatives. Several species of Struthiosaurus are known from similarly aged rocks from other ancient European islands, as are many other rhabdodontid species.