Open Paleo

Unenlagiinae

Bonaparte, 1999 Type genus Unenlagia

Its genera lived 100.5–66.0 million years ago Late Cretaceous
Late Cretaceous stages

Unenlagiinae is a clade of long-snouted, paravian theropod dinosaurs known mainly from the Late Cretaceous of South America, with most members discovered in Argentina and additional forms reported from Antarctica and possibly Australia. The group includes Unenlagia, Buitreraptor, Austroraptor, Neuquenraptor, and Rahonavis among others, ranging from turkey-sized, long-armed predators to Austroraptor, which reached roughly 5 to 6 meters and ranks among the largest dromaeosaurids. Members are distinguished by very elongated, lightly built snouts bearing numerous small teeth, a tail stiffened by long chevrons and vertebral processes, a reduced second toe claw, a backward-oriented pubis, and slender hindlimbs with a subarctometatarsalian foot. These slender feet and less rigid joints likely gave them greater running speed than their Laurasian relatives, suiting them to catching smaller, faster prey. Their distinctive anatomy is thought to reflect the geographic isolation of Gondwana following the breakup of Pangaea. Their placement relative to Dromaeosauridae and Avialae remains contested (see dispute).

Under dispute

The position of Unenlagiinae is contested. Most analyses recover it as an early-diverging clade within Dromaeosauridae (Turner and colleagues, 2012; Brum and colleagues, 2021), the arrangement followed. Hartman and colleagues (2019) instead recover unenlagiines and halszkaraptorines together as Unenlagiidae, the sister group of a dromaeosaurid plus troodontid clade, while Agnolín and Novas (2013) place Unenlagiidae on the avialan stem (Averaptora), closer to birds than to Dromaeosaurus; Motta and colleagues (2020), using the Agnolín and Novas dataset, recover Overoraptor and Rahonavis rather than the unenlagiids as the sister group of Avialae. It is placed conservatively within Dromaeosauridae following the prevailing view.

Diagnosis

  1. Elongate, low snout with a high tooth count
  2. Small, weakly recurved teeth with reduced or absent serrations
  3. Metatarsal III not pinched proximally (subarctometatarsalian condition in some members)
  4. Supraacetabular crest of the ilium reduced, not forming a hood over the acetabulum
  5. Vertically oriented pubis
  6. Ilium with a concave dorsocaudal margin

Genera placed directly in Unenlagiinae

  • Austroraptor Novas et al., 2009 Maastrichtian (72.2–66.0 Ma)Argentina
  • Buitreraptor Makovicky et al., 2005 Cenomanian (100.5–93.9 Ma)Argentina
  • Diuqin Porfiri et al., 2024 Santonian (85.7–83.6 Ma)Argentinaunder dispute
  • Kank Motta et al., 2026 Maastrichtian (72.2–66.0 Ma)Argentinaunder dispute
  • Neuquenraptor Disputed Novas & Pol, 2005 Turonian–Coniacian (93.9–85.7 Ma)Argentina
  • Unenlagia Novas & Puerta, 1997 Turonian–Coniacian (93.9–85.7 Ma)Argentina
  • Ypupiara Brum et al., 2021 Maastrichtian (72.2–66.0 Ma)Brazilunder dispute

References

  1. Bonaparte, J. F. (1999). Tetrapod faunas from South America and India: a palaeobiogeographic interpretation. Proceedings of the Indian National Science Academy 65A(3): 427-437.

    Named the family Unenlagiidae, spelled "Unenlagidae" in the text, for Unenlagia and a Malagasy genus, from which the subfamily Unenlagiinae takes its authorship by coordination.

    bonaparte1999e
  2. Turner, A. H.; Makovicky, P. J.; Norell, M. A. (2012). A Review of Dromaeosaurid Systematics and Paravian Phylogeny. Bulletin of the American Museum of Natural History 371: 1-206. doi:10.1206/748.1

    Emended diagnosis and stem-based definition of Unenlagiinae; recovered it as an early-diverging clade within Dromaeosauridae.

    turner2012a
  3. Brum, A. S.; Pêgas, R. V.; Bandeira, K. L. N.; Souza, L. G.; Campos, D. A.; Kellner, A. W. A. (2021). A new unenlagiine (Theropoda, Dromaeosauridae) from the Upper Cretaceous of Brazil. Papers in Palaeontology 7(4): 2075-2099. Wiley. doi:10.1002/spp2.1375

    Supported the adopted Unenlagiinae arrangement in describing a new unenlagiine dromaeosaurid.

    brum2021a
  4. 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

    Recovered unenlagiines and halszkaraptorines together as Unenlagiidae outside Dromaeosauridae.

    hartman2019a
  5. Motta, M. J.; Agnolín, F. L.; Brissón Egli, F.; Novas, F. E. (2020). New theropod dinosaur from the Upper Cretaceous of Patagonia sheds light on the paravian radiation in Gondwana. The Science of Nature 107(3). Springer Science and Business Media LLC. doi:10.1007/s00114-020-01682-1

    Described Overoraptor and recovered it with Rahonavis as the sister group of Avialae, separate from the unenlagiids, using the dataset of Agnolín and Novas (2013).

    motta2020a
  6. Agnolín, F. L.; Novas, F. E. (2013). Avian Ancestors. SpringerBriefs in Earth System Sciences. Springer Netherlands. doi:10.1007/978-94-007-5637-3

    Treated unenlagiines as avialans closer to birds rather than dromaeosaurids.

    agnolín2013a
  7. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Adopts Unenlagiinae as an early-diverging clade within Dromaeosauridae.

    jones2026c
  8. Makovicky, P. J.; Apesteguía, S.; Agnolín, F. L. (2005). The earliest dromaeosaurid theropod from South America. Nature 437(7061): 1007-1011. Springer Science and Business Media LLC. doi:10.1038/nature03996

    Described Buitreraptor and placed Bonaparte's family as the subfamily Unenlagiinae within Dromaeosauridae.

    makovicky2005a