Flat-headed dinosaur lived on an island of dwarf creatures
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A previously unknown dinosaur with a remarkably flat head lived about 70 million years ago on an island that was home to tiny prehistoric creatures.
Discovered in what is now western Romania, the Transylvanosaurus platycephalus (flathead reptile from Transylvania) was 2 meters (6 feet) long – a relatively small size for a dinosaur, according to a new study. The skull bones were excavated in 2007 from a river bed of the Haţeg Basin.
In the Cretaceous period, this region of Romania was a tropical archipelago. Dinosaurs lived there smaller than their relatives elsewhere; paleontologists think these dinosaurs were an example of what biologists call “island rule,” where large animals isolated on islands become smaller or stunted over time and small animals grow larger.
For example, sauropods, the largest type of dinosaur that ever lived, reached average heights of a puny 6 meters (almost 20 feet) on the archipelago, compared to 15 to 20 meters (49.2 to 65.6 feet) typical for the group.
However, the mechanism causing such changes is not fully understood, but may be related to a lack of resources.
The dinosaur bones could 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, the weather and scavengers would have quickly destroyed all of its bones and we would never have found out,” says study co-author Felix Augustin, a paleontologist and doctoral student. pupil at the University of Tübingen in Germany, it said in a press release.
None of the bones the researchers discovered was longer than 12 centimeters (about 5 inches), but they revealed remarkable details about the small herbivorous dino that would have walked on two legs and had a powerful, thick tail. The research team said it was possible to discern the outline of Transylvanosaurus’ brain.
“We were able to see the impressions, and thus the proportions, of different brain sections – more specifically, of the olfactory bulb (the part of the brain responsible for the sense of smell) and the cerebrum, which serves different functions from sensory processing to memory,” Augustin said via email.
“The next step would be to compare the proportions of the brain and eye with other related species, as this may provide information about which senses were important to Transylvanosaurus,” he added.
The Haţeg Basin has been a hotbed for dinosaur discoveries. Ten dinosaur species have already been identified during excavations in the region, with the first dinosaur being discovered in 1900. The Transylvanosaurus platycephalus is the first new dinosaur species discovered there in 10 years after a small, long-necked carnivore and herbivore was found in 2010, Augustin said.
Transylvanosaurus was a herbivore and part of a family of dinosaurs known as Rhabdodontidae that were common during the late Cretaceous era. Its head was much wider than those of other Rhabdodontidae species, the study said.
Exactly how Transylvanosaurus ended up in the eastern part of what was the European archipelago remains unclear.
Researchers believe this type of dinosaur could have originated in what is now France, where fossils of its closest relatives have been found, and somehow ended up in the region – perhaps by swimming, or by fluctuations in sea levels or tectonic processes that created a land bridge.
“They had powerful legs and a powerful tail,” Augustin said of the Transylvanosaurus. “Most species, especially reptiles, can swim from birth.”
Another possibility is that several lines of rhabdodontid species evolved in parallel in East and West Europe.
Regardless of geographic origin, the newly discovered species helps disprove assumptions that there was low diversity of dinosaurs and other fauna in the Late Cretaceous Period, the researchers said. In addition to the dwarf dinosaurs, the Haţeg Basin was also home to crocodiles, giant pterosaurs (flying reptiles), and turtles – before dinosaurs became extinct 66 million years ago.
“Almost every land animal on this island was quite small,” Augustin said via email. “An exception was the pterosaurs, some of which reached gigantic body sizes – the reason for this is probably that they could fly and so were not so badly affected by the island’s limited resources.”
The research was published Nov. 23 in the Journal of Vertebrate Paleontology.
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