Unenlagiines
Temporal range: Late Cretaceous, 94–70 Ma
Unenlagiinae.jpg
Many genera of the family
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: Dromaeosauridae
Subfamily: Unenlagiinae
Bonaparte, 1999
Type species
Unenlagia comahuensis
Novas & Puerta, 1997
Genera

Unenlagiinae is a subfamily of dromaeosaurid theropods. Unenlagiines are known from South America and Antarctica.[1] With possible Unenlagiines being known from North America, Madagascar and Europe.[2]

Description

Buitreraptor skeleton
Austroraptor preying on fish, depicting a piscivore life-style

Most unenlagiines have been discovered in Argentina. The largest was Austroraptor, which measured up to 5–6 m (16.4–19.7 ft) in length, making it also one of the largest dromaeosaurids.[3] The subfamily is distinguished from other dromaeosaurids by a tail stiffened by lengthy chevrons and superior processes, sharp articulate claws, and a posteriorly oriented pubis.[citation needed] Their distinct anatomy from Laurasian dromaeosaurids was likely a consequence of the breakup of Pangaea into Gondwana and Laurasia, where the geological isolation of unenlagiines from their relatives resulted in allopatric speciation.[4] A 2020 study performed by Gianechini et al., indicates that the unenlagiine dromaeosaurids of Gondwana possessed different hunting specializations than the eudromaeosaurs from Laurasia. The shorter second phalanx in the second digit of the foot of eudromaeosaurs allowed for increased force to be generated by that digit, which, combined with a shorter and wider metatarsus, and a noticeable marked hinge‐like morphology of the articular surfaces of metatarsals and phalanges, possibly allowed eudromaeosaurs to exert a greater gripping strength than unenlagiines, allowing for more efficient subduing and killing of large prey. In comparison, the unenlagiine dromaeosaurids possess a longer and slender subarctometatarsus, and less well‐marked hinge joints, a trait that possibly gave them greater cursorial capacities and allowed for greater speed than eudromaeosaurs. Additionally, the longer second phalanx of the second digit allowed unenlagiines fast movements of their feet's second digits to hunt smaller, faster types of prey. These differences in locomotor and predatory specializations may have been a key feature that influenced the evolutionary paths that shaped both groups of dromaeosaurs in the northern and southern hemispheres, respectively.[5]

Classification

During the description of Halszkaraptor in 2017, Cau et al. published a phylogenetic analysis of the Dromaeosauridae, in which, members of the Unenlagiinae are classified as:[6]

Unenlagiinae

Austroraptor

Buitreraptor

Unenlagia comahuensis

Unenlagia paynemili

Neuquenraptor

In 2019, during the description of Hesperornithoides, many Paravian groups were examined for the inclusion of this new genus, including the Unenlagiinae. The analysis ended in the inclusion of Rahonavis, Pyroraptor, Dakotaraptor and Ornithodesmus to the Unenlagiinae.[7]

Unenlagiinae

Austroraptor

Buitreraptor

Pyroraptor

Pamparaptor

Rahonavis

Ornithodesmus

Dakotaraptor

Unenlagia

See also

References

  1. ^ "Unenlagiinae". Paleobiology Database. Retrieved 31 July 2013.
  2. ^ Hartman, Scott; Mortimer, Mickey; Wahl, William R.; Lomax, Dean R.; Lippincott, Jessica; Lovelace, David M. (2019). "A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight". PeerJ. 7: e7247. doi:10.7717/peerj.7247. PMC 6626525. PMID 31333906.
  3. ^ Orozco, José (December 17, 2008). ""Bizarre" New Dinosaur: Giant Raptor Found in Argentina". National Geographic News. Retrieved 2017-12-12.
  4. ^ GIANECHINI, FEDERICO A. (2011). "Unenlagiinae revisited: dromaeosaurid theropods from South America" (PDF). Anais da Academia Brasileira de Ciências (in English and Spanish). Ciudad Autónoma de Buenos Aires, Argentina: Brazilian Academy of Sciences. 83 (1): 163–195. doi:10.1590/s0001-37652011000100009. Retrieved 2017-12-12.
  5. ^ Gianechini, Federico A.; Ercoli, Marcos D.; Díaz-Martínez, Ignacio. "Differential locomotor and predatory strategies of Gondwanan and derived Laurasian dromaeosaurids (Dinosauria, Theropoda, Paraves): Inferences from morphometric and comparative anatomical studies". Journal of Anatomy. doi:10.1111/joa.13153.
  6. ^ Cau, A.; Beyrand, V.; Voeten, D.; Fernandez, V.; Tafforeau, P.; Stein, K.; Barsbold, R.; Tsogtbaatar, K.; Currie, P.; Godrfroit, P. (6 December 2017). "Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs". Nature. 552 (7685): 395–399. Bibcode:2017Natur.552..395C. doi:10.1038/nature24679. PMID 29211712.
  7. ^ Hartman, Scott; Mortimer, Mickey; Wahl, William R.; Lomax, Dean R.; Lippincott, Jessica; Lovelace, David M. (2019). "A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight". PeerJ. 7: e7247. doi:10.7717/peerj.7247. PMC 6626525. PMID 31333906.