The isolated and unique environments of islands can produce some… interesting results amongst native species. Take Madagascar for instance. Presently, Madagascar is home to a variety of strange animals like lemurs, aye-ayes and the fossa. The habitats of Madagascar have fueled their distinct evolution over the course of generations, enabling these strange animals to thrive unencumbered by competition from other animals. This trend of unique evolution as a result of island life is demonstrated thoroughly in the fossil record, and in no place is this more apparent than in Haţeg country, Romania.
During the late Cretaceous period, Europe was comprised of a vast chain of islands comparable to present-day Oceania. Amongst this chain was Haţeg island, a moderately sized landmass roughly the size of Austria (approximately 80,000 km2) (1)(2). As was common in the Cretaceous, the fauna of Haţeg was primarily comprised of dinosaurs, crocodiles, pterosaurs, and various mammal species. The difference between Haţeg and the rest of the world? Well, the dinosaurs happened to be dwarfs, the birds of the island were as big as their dinosaurian cousins and the pterosaurs? Yeah, they ate the dinosaurs. Add that on to it being first discovered by an enigmatic and quite frankly crazy Hungarian baron and you’ve got one interesting location.
They are Exactly Like You in Every Way… Except 1/60 Your Size
Haţeg’s dwarf dinosaurs were nothing short of shocking, if not adorable. To illustrate the extreme size differential, I will contrast the American sauropod Alamosaurus with Magyarosaurus, a sauropod species from Haţeg. Both animals lived at the same time, some 70 million years ago; the only difference between them was their respective habitats. At a staggering 26 meters long and with a conservative weight estimate of 38 tonnes, Alamosaurus was amongst the largest animals ever to walk the earth (3). On the other hand, Magyarosaurus was only about 6 meters long and would have weighed slightly over 500 kilograms (3). The difference is so immense that the just leg of Alamosaurus would have weighed almost as much as Magyarosaurus.
Magyarosaurus wasn’t the only dwarf dinosaur living on Haţeg. Other dwarf genera included the hadrosaurid Telmatosaurus, the rhabdodontid Zalmoxes, the nodosaurid Struthiosaurus and the sauropod Paludititan (3)(4). All of these genera were close relatives to their mainland counterparts, with the obvious exception of being significantly smaller. Studies undertaken on the bone chemistry of some genera have revealed that the dinosaurs of Haţeg were in fact adults (4). The question remains: why were the dinosaurs of Haţeg so small?
While Haţeg Island was fairly large, it didn’t have the resources required to support herds of large herbivorous dinosaurs for extended periods. In order to accommodate the limited amounts of vegetation, the ancestors of dinosaurs like Magyarosaurus shrunk in size drastically to ensure that they did not eat themselves into extinction. The concept of shrinking to accommodate life on islands is known as insular dwarfism. There is significant evidence of insular dwarfism within the fossil record, particularity amongst elephants and primates (1). When faced with the prospects of island extinction, it would seem that nature leans towards dwarfism more times than not.
The Hungarian Dinosaur Baron
The concept of insular dwarfism was first introduced by Baron Franz Nopcsa, the man who first discovered the dinosaurs of Haţeg. It was truly hard for me to find a word that quite encapsulated Nopcsa and his life. After all, this was a man who was a ground-breaking geologist and paleontologist; a spy during WW1; attempted to conquer and then nominated himself to become king of Albania; and, would routinely vanish and reappear on a dime (1). I’m pretty sure that “aristocrat” would suit him well, but since I cannot say for sure, I’ll leave his title vacant.
Nopcsa’s contributions to the field of paleontology are remarkable given that his work came at the turn of the 20th century. His discoveries of dinosaurs like Magyarosaurus and Struthiosaurus led him to the conclusion that Haţeg was an island and used their diminutive sizes to create the concept of insular dwarfism (1). Rather shockingly, he proposed that birds were the direct descendants of dinosaurs and that dinosaurs were warm blooded almost a century before these theories became prevalent in paleontological communities (1). Unfortunately, his arrogant nature led to disdain from individuals within scientific communities who disregarded his theories and their potential ramifications. Regardless, it is safe to say that Nopcsa was a paleontologist ahead of his time.
Is it a Dinosaur? Or a Big Bird?
One interesting product of Haţeg was Balaur bondoc, a mysterious genus of theropod dinosaur. After being initially described as a genus of dromaeosaurid (raptor) in 2010, subsequent studies have reassigned Balaur to be within the Avialan class; in other words, Balaur was a large flightless bird (5). The initial assessment of Balaur as a dromaeosaurid was due to the combination of its fairly large size (comparable to that of Velociraptor) and presence of killing claws on its feet (5). However, a closer examination of Balaur’s anatomy points heavily towards it being an avian as opposed to a raptor.
First, Balaur didn’t have just one claw on each foot; it had two (1). This strange and admittedly terrifying trait was unique to Balaur amongst raptors, as all other genera have just a single claw. Second, Balaur’s hand was comprised of two fingers as opposed to the uniform three present in other raptors (1). Finally, the skeleton of Balaur is stockier and contains more fused bones than what is typical amongst raptors (6). The presence of these traits would be far more logical if Balaur was a genus of flightless bird instead of a raptor. While further research is required to confirm its status as a bird, it would seem that the odd adaptations of Balaur were indeed a result of Haţeg’s isolation.
The Terror from the Sky…
The dwarfism exhibited by Haţeg’s dinosaur population was contrasted by Hatzegopteryx, a pterosaur which underwent a form of gigantism. With a height of 5 meters and a wingspan that was over 11 meters across, Hatzegopteryx was amongst the largest animals ever to fly (1). Researchers have revealed that giant pterosaurs like Hatzegopteryx were surprisingly competent when maneuvering on the ground, allowing them to walk relatively fast in search of prey (7). Their apparent dexterity on the ground has led some paleontologists to hypothesize that they may not have actually been able to fly, but rather hunted prey exclusively on the ground.
Speaking of prey, what exactly did Hatzegopteryx eat? Well, it ate the dinosaurs of Haţeg! While Hatzegopteryx was a lightweight proportionate to its size (about 200 kg/440 pounds), it had a strong neck that would have been able to lift fairly heavy animals up to swallow (8). This neck wasn’t strong enough to lift a fully grown Magyarosaurus, but it definitely could have swallowed juvenile individuals. Additionally, the beak of Hatzegopteryx may have been able to inflict injury on potential prey by essentially stabbing them. To make it simple, think of Hatzegopteryx as a prehistoric Heron; after spotting prey in the sky and flying over, it could either swallow it whole or poke it to death. In a world dominated by dinosaurs, Hatzegopteryx managed to take refuge as an alpha predator in the only place it could: the land of dwarfs.
The fossils of Haţeg encompass over 15 million years of geological time and lead all the way into the K-T extinction some 65 million years ago. Unlike the dinosaurs of King Kong, living on an island did not exclude the animals of Haţeg from extinction. Like their relatives across the world, the dwarf dinosaurs and giant pterosaurs of Haţeg were ultimately doomed.
I do not take credit for any images found within this article.
Magyarosaurus size courtesy of Wikipedia, found here
Franz Nopcsa courtesy of Wikipedia, found here
Balaur courtesy of Emily Willoughby, found here
Hatzegopteryx eating Zalmoxes also courtesy of Dr. Mark Witton (wonder if I like his art….) found here
- Pickrell, John. Weird Dinosaurs: the Strange New Fossils Challenging Everything We Though We Knew. Columbia University Press, 2017.
- “AUSTRIA.” Encyclopedia of the Nations, 2020, www.nationsencyclopedia.com/economies/Europe/Austria.html.
- Molina-Pérez Rubén, et al. Dinosaur Facts and Figures: the Sauropods and Other Sauropodomorphs. Princeton University Press, 2020.
- Benton, Michael J., et al. “Dinosaurs and the Island Rule: The Dwarfed Dinosaurs from Haţeg Island.” Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 293, no. 3-4, 2010, pp. 438–454., doi:10.1016/j.palaeo.2010.01.026.
- Cau, Andrea, et al. “The Phylogenetic Affinities of the Bizarre Late Cretaceous Romanian Theropod Balaur Bondoc (Dinosauria, Maniraptora): Dromaeosaurid or Flightless Bird?” PeerJ, 2015, doi:https://doi.org/10.7717/peerj.1032.
- Naish, Darren. “The Romanian Dinosaur Balaur Seems to Be a Flightless Bird.” Scientific American Blog Network, Scientific American, 20 June 2015, blogs.scientificamerican.com/tetrapod-zoology/the-romanian-dinosaur-balaur-seems-to-be-a-flightless-bird/.
- Witton, Mark P., and Darren Naish. “A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology.” PLoS ONE, vol. 3, no. 5, 2008, doi:10.1371/journal.pone.0002271.
- Naish, Darren, and Mark P. Witton. “Neck Biomechanics Indicate That Giant Transylvanian Azhdarchid Pterosaurs Were Short-Necked Arch Predators.” PeerJ, vol. 5, 2017, doi:10.7717/peerj.2908.