Unenlagia

Last updated

Unenlagia
Temporal range: Late Cretaceous
~89  Ma
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Unenlagia.jpg
Illustration of known material of U. comahuensis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: Dromaeosauridae
Subfamily: Unenlagiinae
Genus: Unenlagia
Novas & Puerta, 1997
Species
  • U. comahuensisNovas & Puerta, 1997 (type)
  • U. paynemiliCalvo, Porfiri & Kellner, 2004

Unenlagia (meaning "half-bird" in Latinized Mapudungun) is a genus of dromaeosaurid theropod dinosaur that lived in South America during the Late Cretaceous period. [1] The genus Unenlagia has been assigned two species: U. comahuensis, the type species described by Novas and Puerta in 1997, [1] and U. paynemili, described by Calvo et al. in 2004. [2]

Contents

Discovery and naming

Casts of U. paynemili fossils; today the claw is considered one of the hand unguals, not of the foot as shown here Unenlagia fossils.jpg
Casts of U. paynemili fossils; today the claw is considered one of the hand unguals, not of the foot as shown here

In 1996 in the Neuquén province of Argentina a skeleton of a theropod was discovered in the Sierra del Portezuelo and reported the same year. [3] In 1997 Fernando Emilio Novas and Pablo Puerta named and described Unenlagia comahuensis. The generic name is derived from Mapuche uñùm, 'bird', and llag, 'half', in reference to the fact that the describers considered the species to be a link between birds and more basal theropods. The specific name refers to the Comahue, the region the find was made. [1]

The holotype specimen, MCF PVPH 78, was uncovered in layers of the Portezuelo Formation dating to the Coniacian. It consists of a partial skeleton lacking the skull but including vertebrae, a sacrum, ribs, chevrons, a scapula, a humerus, a partial pelvis, a femur and a tibia. [1]

In 2002 near the Lago Barreales a second skeleton was uncovered and reported in 2003. [4] In 2004 it was named and described by Jorge Calvo, Juan Porfiri and Alexander Kellner as a second species: Unenlagia paynemili. The specific name honours Maximino Paynemil, the chief of the Paynemil community. The holotype is MUCPv-349, a partial skeleton consisting of a humerus and two pubes. Several paratypes were also assigned: MUCPv-343, a claw; MUCPv-409, a partial ilium; MUCPv-415, a phalanx and MUCPv-416, a vertebra. [2]

Some researchers consider Neuquenraptor to be a junior subjective synonym of Unenlagia. [5]

Description

Size comparison with a 1.7 m tall human Unenlagia size.png
Size comparison with a 1.7 m tall human

The body length of Unenlagia has been disputed, due to the fact that only the leg length is well known and it is uncertain whether this should be extrapolated using the proportions of the low-slung Dromaeosauridae or the long-legged basal birds. [1] Estimates have thus varied between a length of 3.5 m (11 ft) and a weight of 75 kg (165 lb) on the one hand, [6] and a length of just 2 m (6.6 ft) on the other. [7] However, Thomas Holtz has estimated Unenlagia at 2.3 m (7.5 ft) long and 9.1-22.7 kg (20-50 lbs) in weight. [8] Likewise, the interpretation of the head form has changed from a shorter-snouted dromaeosaurid condition to the elongated shape known from the later discovered related genera Buitreraptor and Austroraptor .

Life restoration of U. comahuensis Unenlagia comahuensis .jpg
Life restoration of U. comahuensis

Novas and Puerta found that the pelvic region of Unenlagia, especially the form of the ilium, was very similar to that of the early bird Archaeopteryx . [1] The shoulder girdle of Unenlagia was originally interpreted as if it was adapted for flapping, with a flat scapula positioned on top of the ribcage, making the shoulder joint point more laterally. [1] However, in 2002 Kenneth Carpenter pointed out that this would imply that the shoulder-blade was dorsoventrally flattened instead of laterally as with other theropods and that it thus were more likely the scapula was located on the side of the ribcage. [9] This conformed to a later hypothesis by Philip Senter that non-avian theropods like Unenlagia were unable to lift their forelimbs above their back, as even would still have been the case for the basalmost bird Archaeopteryx . [10] South American workers have remained unconvinced though, countering that a laterally positioned scapula would make the coracoid of Unenlagia jut into its ribcage, which seems anatomically implausible. [7]

Classification

Novas and Puerta in the original description considered Unenlagia a sister taxon of the birds, which would make it a basal member of the Avialae sensu Gauthier 1986.

However, in 1999 Mark Norell and Peter Makovicky stated that Unenlagia was a member of the Dromaeosauridae. [11] [12] Unenlagia would have belonged to the extremely bird-like Gondwanan clade of dromaeosaurids called the Unenlagiinae, and be closely related to species such as Buitreraptor and Neuquenraptor (which might be the same species as Unenlagia). Makovicky et al. in 2005 also recovered the 'flying raptor' Rahonavis as a member of this group, which would mean that either Unenlagia is secondarily flightless, having evolved from flying, Rahonavis-like ancestors, or that bird-like flight evolved at least twice. [13] Norell et al. in 2006 also found Rahonavis to be the sister taxon of Unenlagia. [14]

This position has not been unanimously accepted. In 2011 Novas and Federico Agnolín published a study in which a Unenlagiidae was positioned within Avialae. [15]

Below is a cladogram conducted by Hartman et al. 2019, in which Unenlagia is found to be a more derived member alongside Dakotaraptor : [16]

Unenlagiinae

Austroraptor

Buitreraptor

Pyroraptor

Pamparaptor

Rahonavis

Dakotaraptor

Unenlagia

This cladogram is from Motta et al., 2020, showing Unenlagia being more derived than traditional dromaeosaurids: [17]

Paraves

Troodontidae

Eumaniraptora

Dromaeosauridae

Microraptoria

Unenlagiidae

Austroraptor

Buitreraptor

Unenlagia

Overoraptor

Rahonavis

Avialae
Archaeopterygidae

Alcmonavis

Wellnhoferia

Archaeopteryx

Anchiornithidae

Xiaotingia

Anchiornis

Jeholornis

Pygostylia

See also

Related Research Articles

<span class="mw-page-title-main">Dromaeosauridae</span> Family of theropod dinosaurs

Dromaeosauridae is a family of feathered coelurosaurian 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 δρομαῖος (dromaîos), meaning 'running at full speed', 'swift', and σαῦρος (saûros), meaning 'lizard'. In informal usage, they are often called raptors, a term popularized by the film Jurassic Park; several genera include the term "raptor" directly in their name, and popular culture has come to emphasize their bird-like appearance and speculated bird-like behavior.

<i>Neuquenraptor</i> Extinct genus of dinosaurs

Neuquenraptor is a genus of dromaeosaurid theropod dinosaurs that lived in South America during the Late Cretaceous in what is now the Portezuelo Formation of Argentina. It is one of the first dromaeosaurids found in the Southern Hemisphere.

<i>Buitreraptor</i> Dromaeosaurid dinosaur genus from the Late Cretaceous

Buitreraptor is a genus of dromaeosaurid dinosaurs that lived during the Late Cretaceous of Argentina at the Candeleros Formation. Buitreraptor was described in 2005 and the type species is Buitreraptor gonzalezorum. It was rooster-sized and had a very elongated head with many small teeth.

<i>Adasaurus</i> Extinct genus of dinosaurs

Adasaurus is a genus of dromaeosaurid dinosaur that lived in Asia during the Late Cretaceous period about 70 million years ago. The genus is known from two partial specimens found in the Nemegt Formation of Mongolia that were partially described in 1983 by the paleontologist Rinchen Barsbold.

<i>Rahonavis</i> Extinct genus of dinosaurs

Rahonavis is a genus of bird-like theropods from the Late Cretaceous of what is now northwestern Madagascar. It is known from a partial skeleton found by Catherine Forster and colleagues in Maevarano Formation rocks at a quarry near Berivotra, Mahajanga Province. Rahonavis was a small predator, at about 70 centimetres (2.3 ft) long and 0.45-2.27 kg, with the typical Velociraptor-like raised sickle claw on the second toe. It was originally the first African coelurosaur until the Nqwebasaurus was discovered in 2000.

<i>Megaraptor</i> Extinct genus of dinosaurs

Megaraptor is a genus of large theropod dinosaur that lived in the ages of the Late Cretaceous. Its fossils have been discovered in the Patagonian Portezuelo Formation of Argentina, South America. Initially thought to have been a giant dromaeosaur-like coelurosaur, it was classified as a neovenatorid allosauroid in previous phylogenies, but more recent phylogeny and discoveries of related megaraptoran genera has placed it as either a basal tyrannosauroid or a basal coelurosaur with some studies still considering it a neovenatorid.

<i>Pyroraptor</i> Extinct genus of dinosaurs

Pyroraptor is an extinct genus of paravian dinosaur, probably a dromaeosaurid or unenlagiid, from the Late Cretaceous Ibero-Armorican island, of what is now southern France and northern Spain. It lived during the late Campanian and early Maastrichtian stages, approximately 83.5 to 70.6 million years ago. It is known from a single partial specimen that was found in Provence in 1992, after a forest fire. The animal was named Pyroraptor olympius by Allain and Taquet in 2000.

The Portezuelo Formation is a geologic formation of Late Cretaceous age, outcropping in the Mendoza, Río Negro and Neuquén provinces of Argentina. It is the fourth-oldest formation in the Neuquén Group and the older of the two formations in the Río Neuquén Subgroup. Formerly, that subgroup was treated as a formation, and the Portezuelo Formation was known as the Portezuelo Member.

<span class="mw-page-title-main">Paraves</span> Clade of all dinosaurs that are more closely related to birds than to oviraptorosaurs

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<i>Orkoraptor</i> Extinct genus of dinosaurs

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<i>Aerosteon</i> Extinct genus of dinosaurs

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<i>Austroraptor</i> Genus of theropod dinosaurs

Austroraptor is a genus of dromaeosaurid theropod dinosaur that lived during the Campanian and Maastrichtian ages of the Late Cretaceous period in what is now Argentina.

<i>Pamparaptor</i> Extinct genus of dinosaurs

Pamparaptor is an extinct genus of maniraptoran theropod dinosaur from the Late Cretaceous Portezuelo Formation of the Neuquén province in Argentine Patagonia. Its precise classification is uncertain, but it is definitely a member of Paraves and probably a deinonychosaur. The authors who described it have argued that it is a dromaeosaurid. The genus contains a single species, P. micros, which is known from a single specimen consisting of a mostly complete and fully-articulated left foot, which preserves the iconic dromaeosaur-like “killing claw”.

Bonapartenykus is a monospecific genus of alvarezsauroid dinosaur from Argentina that lived during the Late Cretaceous (Campanian-Maastrichtian) in what is now the upper Allen Formation of the Río Negro Province. The type and only species, Bonapartenykus ultimus, is known from a nearly articulated but partial skeleton that was found in close association to two incomplete eggs and several clusters of eggshells belonging to the oogenus Arriagadoolithus. Bonapartenykus was named in 2012 by Federico L. Agnolin, Jaime E. Powell, Fernando E. Novas and Martin Kundrát. Bonapartenykus has an estimated length of 2.5 m (8.2 ft) and weight of 72 kg (159 lb), making it the largest member of the clade Alvarezsauroidea.

<span class="mw-page-title-main">Timeline of dromaeosaurid research</span>

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<span class="mw-page-title-main">Unenlagiidae</span> Extinct family of dinosaurs

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<i>Argentinadraco</i> Genus of azhdarchoid pterosaur from the Late Cretaceous

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Kaikaifilusaurus is an extinct genus of rhynchocephalians in the family Sphenodontidae from the Late Cretaceous of South America. Fossils of the genus were found in Cenomanian sediments of the Candeleros Formation and Turonian layers of the Huincul Formation, both of the Neuquén Basin and the Albian strata of the Cerro Barcino Formation in the Cañadón Asfalto Basin, all in Patagonia, Argentina. The genus contains two species, K. minimus and the type species K. calvoi.

<i>Overoraptor</i> Extinct genus of theropod dinosaurs

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References

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  16. 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. doi: 10.7717/peerj.7247 . PMC   6626525 . PMID   31333906.
  17. Matías J. Motta; Federico L. Agnolín; Federico Brissón Egli; Fernando E. Novas (2020). "New theropod dinosaur from the Upper Cretaceous of Patagonia sheds light on the paravian radiation in Gondwana". The Science of Nature (journal). 107 (3): Article number 24. Bibcode:2020SciNa.107...24M. doi:10.1007/s00114-020-01682-1. hdl: 11336/135530 . PMID   32468191. S2CID   218913199.{{cite journal}}: CS1 maint: multiple names: authors list (link)