Unenlagiidae is a proposed family of eumaniraptoran paravians that includes the subfamilies

Unenlagiinae Unenlagiinae is a subfamily of long-snouted paravian theropods. They are traditionally considered to be members of Dromaeosauridae, though some authors place them into their own family, Unenlagiidae, alongside the subfamily Halszkaraptorinae. ...

and possibly

Halszkaraptorinae Halszkaraptorinae is a basal ("primitive") subfamily of Dromaeosauridae (or possibly Unenlagiidae) that includes the enigmatic genera '' Halszkaraptor'', '' Natovenator'', ''Mahakala'', and ''Hulsanpes''. Halszkaraptorines are definitively known ...

. Fossils of both subfamilies have been found in both

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

n and

Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...

n deposits. The biology of the group suggests that some members were semiaquatic specialists.

Classification

The family Unenlagiidae traditionally includes the same members as the previously named subfamily of

Dromaeosauridae Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning ...

, so Unenlagiidae was often seen as a synonym of Dromaeosauridae. However, since the 2010s, there have been subsequent studies that have questioned this placement, necessitating the revival of the family name. Some have placed unenlagiids as outside Dromaeosauridae, being the sister taxon or closely related to

Avialae Avialae ("bird wings") is a clade containing the only living dinosaurs, the birds. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to deinonychosaurs, though alternative definitions are occasionally used ...

, while others have placed the newly recognized halszkaraptorines in the family, as basal

deinonychosaurs Deinonychosauria is a clade of paravian dinosaurs which lived from the Late Jurassic to the Late Cretaceous periods. Fossils have been found across the globe in North America, Europe, Africa, Asia, South America, and Antarctica,Case, J.A., Marti ...

outside Dromaeosauridae and

Troodontidae Troodontidae is a clade of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil disco ...

. Other recent studies supported the traditional placement of Halszkaraptorinae and Unenlagiinae in Dromaeosauridae, forming no distinct clade. In 2021, Brum ''et al.'' named the clade Unenlagiinia for a unified ''Unenlagia''+''Halszkaraptor'' clade, recovering them as basal dromaeosaurs.Brum, Arthur Souza, Pêgas, Rodrigo Vargas, Bandeira, Kamila Luisa Nogueira, Souza, Lucy Gomes de, Campos, Diogenes de Almeida, & Kellner, Alexander Wilhelm Armin. (2021). A new Unenlagiinae (Theropoda: Dromaeosauridae) from the Late Cretaceous of Brazil. https://doi.org/10.1002/spp2.1375 The following cladogram is from Motta ''et al.'', 2020, showing Unenlagiidae outside dromaeosaurids and more closely related to Avialae:

References

Dromaeosaurs Prehistoric dinosaur families {{theropod-stub