Open Paleo

Balaur

Csiki et al., 2010 BAL-our /ˈbæl.aʊr/

From Romanian balaur ('dragon' of Romanian folklore)

72.2–66.0 million years ago Maastrichtian, Late Cretaceous
Late Cretaceous stages

Balaur is a genus of paravian theropod dinosaur from the Late Cretaceous (Maastrichtian) of what is now Romania. It contains a single species, Balaur bondoc, known from two partial skeletons. Its short, stocky build and double sickle claws on each foot are interpreted as an example of island syndrome on the Late Cretaceous Hațeg Island archipelago.

Under dispute

The position of Balaur, an aberrant island form from the Late Cretaceous of Romania, is highly uncertain. It was described as a velociraptorine (Csiki and colleagues, 2010) and a series of recent analyses again recover it as a velociraptorine (Pei and colleagues, 2020; Turner and colleagues, 2021; Napoli and colleagues, 2021), the placement followed. An intervening set of studies instead argued it is a basal avialan (Cau and colleagues, 2015; Hartman and colleagues, 2019, the latter requiring eight extra steps to make it a dromaeosaurid). It is placed at Dromaeosauridae incertae sedis.

Diagnosis

  1. Fused carpometacarpus with reduced splint-like metacarpal III only 30% the mediolateral width of metacarpal II, digit III nonfunctional
  2. Extremely retroverted pubes and ischia with long axes nearly horizontal, associated with enlarged cuppedicus fossa on laterally everted pubic peduncle
  3. Fused metatarsus (metatarsals II-V fused across much of their lengths), tarsometatarsus substantially wider than distal tibiotarsus
  4. Enlarged functional first pedal digit with hyperextensive ungual (second largest in foot), giving the animal a double set of raptorial claws
  5. Hypertrophied coracoid tubercle projecting anteriorly and laterally as a conical projection that obscures the coracoid foramen in lateral view
  6. Sinuous ridge on lateral surface of distal humerus extending for one-third the length of the bone, unique among all theropods

Species

Balaur bondoc Csiki et al., 2010

Type species

bondoc means 'stocky' in Romanian, referring to the species' robust build

Holotype
EME PV.313 , Erdélyi Múzeum-Egyesület (Transylvanian Museum Society)
Material
Articulated partial postcranial skeleton including dorsal, sacral, and caudal vertebrae and much of the pectoral and pelvic girdles and limbs
Horizon
Sebeș Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
Sebeș Glod, Alba, Romania

Notable specimens

  • FGGUB R.1580, FGGUB R.1581, FGGUB R.1582, FGGUB R.1583, FGGUB R.1584, FGGUB R.1585

    Laboratory of Paleontology, Faculty of Geology and Geophysics, University of Bucharest Found 1997 by Dan Grigorescu largest individual

    Six forelimb elements, the first Balaur bones found, indicating an individual about 45 percent longer than the holotype and recovered from a younger stratum. The unusual arm morphology led to them initially being mistaken for an oviraptorosaur.

    Csiki et al. (2010)

References

  1. Csiki, Z.; Vremir, M.; Brusatte, S. L.; Norell, M. A. (2010). An aberrant island-dwelling theropod dinosaur from the Late Cretaceous of Romania. Proceedings of the National Academy of Sciences 107(35): 15357-15361. Proceedings of the National Academy of Sciences. doi:10.1073/pnas.1006970107 csiki2010b
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026c
  3. Pei, R.; Pittman, M.; Goloboff, P. A.; Dececchi, T. A.; Habib, M. B.; Kaye, T. G.; Larsson, H. C. E.; Norell, M. A.; Brusatte, S. L.; Xu, X. (2020). Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds. Current Biology 30(20): 4033-4046.e8. Elsevier BV. doi:10.1016/j.cub.2020.06.105

    Large paravian phylogeny recovered Balaur as a velociraptorine dromaeosaurid.

    pei2020a
  4. Napoli, J. G.; Ruebenstahl, A. A.; Bhullar, B. A. S.; Turner, A. H.; Norell, M. A. (2021). A New Dromaeosaurid (Dinosauria: Coelurosauria) from Khulsan, Central Mongolia. American Museum Novitates 2021(3982). American Museum of Natural History (BioOne sponsored). doi:10.1206/3982.1

    New dromaeosaurid description's phylogeny supported Balaur's velociraptorine placement.

    napoli2021a
  5. Hartman, S.; Mortimer, M.; Wahl, W. R.; Lomax, D. R.; Lippincott, J.; Lovelace, D. M. (2019). A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ 7: e7247. PeerJ. doi:10.7717/peerj.7247

    Large paravian phylogeny required extra steps to recover Balaur as a dromaeosaurid.

    hartman2019a
  6. Cau, A.; Brougham, T.; Naish, D. (2015). The phylogenetic affinities of the bizarre Late Cretaceous Romanian theropod Balaur bondoc (Dinosauria, Maniraptora): Dromaeosaurid or flightless bird?. PeerJ 3. doi:10.7717/peerj.1032

    Identified Balaur as basal avialan theropod with distinct phylogenetic affinities

    cau2015a
  7. Turner, A. H.; Montanari, S.; Norell, M. A. (2021). A New Dromaeosaurid from the Late Cretaceous Khulsan Locality of Mongolia. American Museum Novitates 2020(3965): 1-46. American Museum of Natural History (BioOne sponsored). doi:10.1206/3965.1

    Contributed to reassessment of Balaur's phylogenetic position.

    turner2021a