The flat-headed dinosaur lived on an island of dwarf creatures

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news of fascinating discoveries, scientific breakthroughs and more.

CNN
—

A previously unknown dinosaur with a remarkably flat head lived about 70 million years ago on an island home to prehistoric dwarf creatures.

Discovered in what is now western Romania, Transylvanosaurus platycephalus (flathead reptile from Transylvania) was 2 meters (6 ft) long – a relatively small size for a dinosaur, according to a new study. His skull bones were found in 2007 in the bed of the Hatseg River.

During the Cretaceous period, this region of Romania was a tropical archipelago. Dinosaurs lived there smaller than their relatives elsewhere; paleontologists believe that these dinosaurs were an example of what biologists call “island management,” where large animals isolated on islands become dwarfed or stunted over time, and small animals grow larger.

Sauropods, the largest type of dinosaur that ever lived, reached an average height of only 6 meters (almost 20 ft) in the archipelago, for example, compared to 15 to 20 meters (49.2 to 65.6 ft) typical for the group.

However, the mechanism that gives rise to such changes is not fully understood, but may be related to resource scarcity.

The dinosaur bones were able to survive for tens of millions of years because the sediments of an ancient river bed protected them.

“If the dinosaur had died and just lay on the ground instead of being partially buried, time and scavengers would have quickly destroyed all of its bones and we would never have known about it,” study co-author Felix Augustin, a paleontologist and Ph.D. a student at the University of Tübingen in Germany, according to a news release.

None of the bones the researchers found was longer than 12 centimeters (about 5 inches), but they revealed a remarkable amount of detail about the small plant-eating dino, which would have walked on two legs and had a powerful, thick tail. It was possible to make out the outlines of Transylvanosaurus’ brain, the research team said.

“We were able to see the impressions and thus the proportions of different brain sections—specifically, the olfactory bulbs (the part of the brain responsible for smell) and the cerebrum, which performs several different functions from sensory processing to memory,” Augustine said by email.

“The next step would be to compare the proportions of the brain and eye with other related species, as this may provide information on what senses were important to Transylvanianosaurus,” he added.

The Hatseg Basin has been a hotbed for dinosaur discoveries. Ten species of dinosaur have already been identified during excavations in the region, with the first dinosaur discovered in 1900. Transylvanosaurus platycephalus is the first new species of dinosaur discovered there in 10 years, after a small carnivore and a long-necked herbivore were discovered in 2010, Augustine said.

Transylvanianosaurus was a herbivore and part of a family of dinosaurs known as the Rhabdodontidae that were common during the late Cretaceous period. Its head was much wider than other Rhabdodontidae species, the study said.

Exactly how Transylvanianosaurus ended up in the eastern part of the European archipelago remains unclear.

Researchers believe that this type of dinosaur may have originated in present-day France, where fossils of its closest relatives have been found, and that it somehow reached the region – perhaps by swimming, or by fluctuations in sea level or tectonic processes that created a land bridge.

“They had powerful legs and a powerful tail,” Augustine said of Transylvanianosaurus. “Most species, especially reptiles, can swim from birth.”

Another possibility is that different lineages of rhabdodontid species evolved in parallel in the eastern and western Europe.

Regardless of its geographic origin, the newly discovered species helps challenge suggestions that there was a low diversity of dinosaurs and other fauna in the late Cretaceous period, the researchers said. As well as pygmy dinosaurs, the Hatzeg Basin was also home to crocodiles, giant pterosaurs (flying reptiles) and turtles – before the dinosaurs went extinct 66 million years ago.

“Almost every land animal on this island was quite small,” Augustine said via email. “The exception was the pterosaurs, some of which reached gigantic body sizes – the reason for this probably being that they could fly and were therefore not as severely affected by the island’s limited resources.”

The study was published on November 23 in Journal of Vertebrate Paleontology.