Researchers have pieced together a set of puzzling fossils from a stocky dinosaur discovered in Romania. The newly described predator helps to flesh out the spotty fossil record of carnivorous animals from Europe's Cretaceous.
The dinosaur, Balaur bondoc, was a sharp-clawed theropod that lived among small island creatures when sea levels were high and the continent of Europe was a series of islands, some 60 million years ago.
"The morphology is so weird we didn't have any idea where to fit them," Zoltan Csiki, of the University of Bucharest, said in a prepared statement. Csiki and colleagues described the new species in a study published online August 30 in Proceedings of the National Academy of Sciences.
Many animals that evolve in isolated environments, such as archipelagos, show signs of the so-called island effect, which can render them smaller and imbue in them some odd characteristics.
For its part, B. bondoc was not much smaller than its close relatives in Asia and North America and measured about six or seven feet long. Its body shape and skeletal characteristics, however, easily distinguish it from other dromaeosaurids of the era. "B. bondoc is heavy, with unexpectedly stocky limbs and fused bones," Mark Norell, of the American Museum of Natural History in New York and coauthor of the paper, said in a prepared statement. The name Balaur bondoc means "stocky dragon" in archaic Romanian.
"It is closely related to animals like Velociraptor and the feathered dinosaurs in China," Csiki said. The dinosaur also had two big extendable claws on its first and second toes that it likely used as hunting weapons. The short legs and arms had fused bones, and the hip's structure suggests the animal had a lot of muscle.
B. bondoc is the most complete middle or late Cretaceous predator from Europe to be described to date. The researchers based their findings on the parts of the skeleton that survived the corrosive eons when it was found more than a decade ago, including parts of the backbone, arms, leg, hip, hand, ribs and tail.
"Balaur is a new breed of predatory dinosaur," Stephen Brusatte, a graduate student at Columbia University and coauthor of the description, said in a prepared statement. "Its anatomy shows that it probably hunted in a different way than its less stocky relatives," which likely relied more on speed and agility. "Compared to Velociraptor, Balaur was probably more of a kick boxer than a sprinter," he said.
Despite the distinct differences from its leaner cousins, B. bondoc seems to be relatively closely related to Asian and North American raptors. "The finding indicates that this area of the world, despite its archipelago geography, had at least intermittent faunal connections with the mainland up to the end of the Cretaceous," Csiki said—a link that was "not really acknowledged until recently," he noted.
The new analysis also helps to underscore other ancient evolutionary anomalies as well as more recent instances of the island effect. "It shows just how unusual the fauna of the area was during the waning years of the dinosaur era," Norell said. "Balaur is thrilling and is a testament to the unusual animals found on islands today."
Image of clawed foot courtesy of Mick Ellison; image of reconstruction courtesy of Mick Ellison/Zoltan Csiki/Matyas Vremir/Stephen Brusatte/Mark Norell/AMNH