Balaur

*Balaur bondoc*

Tim Bradley Artwork

***Balaur bondoc*** (named after balaur, a dragon from Romanian folklore) is a uniquely specialized species of theropod dinosaur. It lived in what is now Romania during the latter part of the Late Cretaceous, 77-65 mya. *Balaur* was described by scientists in August 2010. It is known from a single partial skeleton representing the type specimen. Having been described as a "beefy version of the predatory *Velociraptor*", its name is Romanian language for 'stocky dragon'. Unlike its other relatives within the dromaeosaur family, which includes *Velociraptor*, *Deinonychus*, and the four-winged, gliding dromaeosaur Microraptor *Gui*, this raptor had not just one but two large, retractable, sickle-shaped claws on each foot, and its limbs were proportionally shorter and heavier than those of its other relatives. Given these and nearly twenty other derived traits, the new genus *Balaur* was Biological classification created for this one species. As with other dinosaurs from Hațeg, such as *Magyarosaurus*, a dwarf sauropod, its aberrant features are argued to show the effects of its island habitat on its evolution.

## Description

*Balaur* is an avialan theropod dinosaur estimated to have lived about 70 million years ago in the late Cretaceous (Maastrichtian). Its bones were shorter and heavier than those of other dromaeosaurs. While the feet of most dromaeosaurs bore a single, large "sickle claw" on the second toe which was held retracted off the ground, *Balaur* had large retractable sickle claws on both the first and second toes of each foot.In addition to its strange feet, *Balaur* is unique for its status of being the most complete avialan theropod from the late Cretaceous of Europe. It also possesses a great number of additional autapomorphies, including a reduced and presumably nonfunctional third manual digit.

## Discovery

The first small bones belonging to *Balaur bondoc* consisted of six elements of the front limbs. Named specimens FGGUB R. 1580-1585, these were discovered in 1997 in Romania by Dan Grigorescu, but the morphology of the arm was so unusual that scientists could not correctly combine them, mistaking them for the remains of a oviraptorosaur. The first partial skeleton was discovered in September 2009 in Romania, approximately 2.5 kilometers north of Sebeș, along the Sebeș river in the Sebeș Formation dating from the early Maastrichtian, and was given the preliminary field number *SbG/A-Sk1*. Later it received the holotype inventory number EME VP.313. The discovery was made by the geologist and paleontologist Mátyás Vremir of the Transylvanian Museum Society of Cluj Napoca who sent them for analysis to Zoltán Csiki of the University of Bucharest.The findings were described on August 31, 2010, in the *Proceedings of the National Academy of Sciences*. The 1997 specimens indicate an individual about 45% longer than the holotype; they were also found in a younger stratum.

The generic name *Balaur* (three syllables, stressed on the second /a/) is from the Romanian word for a dragon of Romanian folklore, while the specific epithet *bondoc* (pronounced like "boned oak", meaning "a squat, chubby individual") refers to the small, robust shape of the animal. As the *balaur* is a winged dragon, the name additionally hints at the close relation of *Balaur* to the birds within Panaves. *Bondoc* was chosen by the discoverers also because it is derived from the Turkish *bunduk*, "small ball", thus alluding to the probable Asian origin of the ancestors of *Balaur*.

*Balaur* has four claws on each feet, setting it apart from most theropods.

## Classification

The position of *Balaur* relative to other bird-like dinosaurs and early birds has been difficult to determine. The initial phylogenetic analysis placed *Balaur bondoc* closest to the Asiatic mainland dromaeosaurid species *Velociraptor mongoliensis*. A 2013 study by Brusatte and colleagues, using a modified version of the same data, found it in an unresolved close relationship with the dromaeosaurids *Deinonychus* and *Adasaurus*, with some possible alternative trees suggesting it branched off before the common ancestor of *Deinonychus* and *Velociraptor*, while others maintained it as the closest relative of *Velociraptor*, with *Adasaurus* as their next closest relative.

More recent analyses using different sets of anatomical data have since cast doubt on a dromaeosaurid classification for *Balaur*. In 2013, a larger analysis containing a wide variety of coelurosaurs found that Balaur was not a dromaeosaurid at all, but a basal avialan, more closely related to modern birds than to Jeholornithiformes but more basal than Omnivoropterygiformes. A study published in 2014 found *Balaur* to be sister to Pygostylia. An independent analysis using an expanded version of the original data set (the one that found *Balaur* to be a dromaeosaurid) drew a similar conclusion in 2014. In 2015, researchers Andrea Cau, Tom Brougham, and Darren Naish published a study which specifically attempted to clarify which theropods were close relatives of *Balaur*. While their analysis could not completely rule out the possibility that *B. bondoc* was a dromaeosaurid, they concluded that this result was less likely than the classification of *Balaur* as a non-pygostylian avialan based on several important bird-like features. Many of the presumed unique traits would in fact have been normal for a member of the Avialae. Typical bird features included the degree of fusion of the limb bones, the functional first toe, the first toe claw not being smaller than the second claw, a long penultimate phalanx of the third toe, a small fourth toe claw and a long fifth metatarsal.

On the other hand, some recent studies continue to place Balaur within the Velociraptorinae.

## Behavior

Little is known about the behavior of *Balaur*, but Csiki speculates that it may have been one of the apex predators in its limited island ecosystem, because no larger teeth have ever been found in Romania. He also believes that it likely used its double sickle claws for slashing prey, and that the atrophied state of its hands indicates that it probably did not use them to hunt. One of the original discoverers indicated that it "was probably more of a kickboxer than a sprinter" compared to *Velociraptor*, and was probably able to hunt larger animals than itself. However, the hunting behavior as well as its typical prey are not known.

Italian paleontologist Andrea Cau has speculated that the aberrant features present in *Balaur* may have been a result of this dromaeosaurid being omnivorous or herbivorous instead of carnivorous like typical dromaeosaurids. The lack of the third finger may be a sign of reduced predatory behavior and the robust first toe could be interpreted as a weight-supporting adaptation rather than a weapon. These characteristics are consistent with the relatively short, stocky limbs and wide, swept-back pubis, which may indicate enlarged intestines for digesting vegetation as well as reduced speed.

## Appearance in Jurassic Park and other media

### *Jurassic Park*

Balaur is only mentioned on a plaque display in the Jurassic World: The Exhibition.