Shanag

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Shanag
Temporal range: Early Cretaceous, 130  Ma
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Shanag skull.png
Reconstructed Skull
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Paraves
Family: Dromaeosauridae
Genus: Shanag
Turner et al., 2007
Species:
S. ashile
Binomial name
Shanag ashile
Turner et al., 2007

Shanag is a genus of paravian theropod dinosaur from the Early Cretaceous Period of Mongolia. It may be a dromaeosaurid, but some researchers are skeptical of this classification. The type species is S. ashile.

Contents

Discovery and naming

Shanag was named and described by Alan Turner, Sunny Hai-Ching Hwang and Mark Norell in 2007. The generic name refers to the black-hatted dancers in the Buddhist Cham dance. The specific name refers to the Ashile Formation, the old name for the layers where Shanag was found, used by Henry Fairfield Osborn. [1]

The holotype of Shanag, IGM 100/1119, was discovered in the Öösh Formation, the stratification of which is uncertain but probably dating to the Berriasian-Barremian. Shanag bears a strong resemblance to basal Chinese dromaeosaurids such as Microraptor and Sinornithosaurus , suggesting a close similarity between the fauna of the Öösh deposits, dated tentatively to 130 million years ago, and the Jehol Biota of China (such as the animals found in the roughly contemporary Yixian Formation), during the Early Cretaceous. [1]

Description

Artist's reconstruction of Shanag ashile as a dromaeosaurid. Shanag.jpg
Artist's reconstruction of Shanag ashile as a dromaeosaurid.

Shanag was a small predator, measuring about 1.5 metres (4.9 ft) long and weighing around 5 kilograms (11 lb). [2] Shanag shows a mixture of dromaeosaurid, troodontid and basal avialan traits. [1]

The holotype specimen, about six centimeters long, is composed of an associated uncompressed upper and lower jaw fragment, containing a nearly complete right maxilla with teeth, a partial right dentary with teeth and an attached partial splenial. [1] The fossilized teeth in the specimen were pointed with serrations along the lengths of the posterior teeth, but no anterior teeth were available. [1] Shanag is autopomorphic as it lacks promaxillary fenestra and has interalveolar pneumatic cavities, which separates it from its nearest relative of S. millenii. [1] Its teeth have unusually long root lengths, making up about 70% of the overall tooth length. [1]

As part of the Theropoda group, Shanag had hollow bones and feathers. Though most were not capable of flight, some theropods used their feathers to assist in climbing or simply scrambling up tree trunks. [3] Feathers also allowed for thermoregulation by reducing the amount of airflow near the skin and preventing heat loss. [4] Their wings, though not capable of flight, could be used to stabilize themselves while on their prey via flapping like extant raptor birds. [5] Shanag are also believed to be endothermic based on their high speed and high level of activity. [3]

Sharp middle toe (D-II) claws of dromaeosaurs were initially thought to be for disemboweling prey, and then later tests suggested that due to the claw’s strength and cutting ability that they were used as a climbing tool for scaling the backs of prey larger than themselves. [6] This claim of scaling was later contested, and it was suggested the claws were used to grip and pin down prey similarly to extant birds of prey. [5]

Classification

In 2007, Turner and collaegues assigned Shanag to the Dromaeosauridae. Their cladistic analysis indicated that it was a basal dromaeosaurid but higher in the tree than the Unenlagiinae. [1] Later analyses recovered it in the Microraptorinae. [7] In 2012, Shanag was recovered as a sister taxon to the Unenlagiinae. [8] In 2013, Agnolín and Novas claimed that the traits of Shanag once used to identify the taxon as a dromaeosaurid closely related to the unenlagiines, were actually found in many other groups of paravian theropods such as the troodontids, avialans, and other basal paravians, with some features suggesting that it is more likely an avialan. Thus, they concluded that Shanag can only be identified as a basal averaptoran. [9]

A 2017 study still recovered Shanag as a dromaeosaurid based on phylogenetic analyses, but as a sister taxon to Laurasian dromaeosaurids from the Late Cretaceous and not related to unenlagiines. [10] In 2019, Agnolín and colleagues argued that Shanag cannot be confidently classified as a dromaeosaurid other than being a paravian. [11] In 2024, Porfiri and colleagues classified Shanag and Pyroraptor as sister taxa to unenlagiines, [12] while Wang and Pei recovered Shanag within Serraraptoria which includes microraptorians and eudromaeosaurians. [13]

See also

Related Research Articles

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

Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. 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 discoveries of complete and articulated specimens, have helped to increase understanding about this group. Anatomical studies, particularly studies of the most primitive troodontids, like Sinovenator, demonstrate striking anatomical similarities with Archaeopteryx and primitive dromaeosaurids, and demonstrate that they are relatives comprising a clade called Paraves.

<span class="mw-page-title-main">Deinonychosauria</span> Extinct clade of dinosaurs

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, with fossilized teeth giving credence to the possibility that they inhabited Australia as well. This group of dinosaurs are known for their sickle-shaped toe claws and features in the shoulder bones.

<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>Sinornithosaurus</i> Extinct genus of dinosaurs

Sinornithosaurus is a genus of feathered dromaeosaurid dinosaur from the early Cretaceous Period of the Yixian Formation in what is now China. It was the fifth non–avian feathered dinosaur genus discovered by 1999. The original specimen was collected from the Sihetun locality of western Liaoning. It was found in the Jianshangou beds of the Yixian Formation, dated to 124.5 million years ago. Additional specimens have been found in the younger Dawangzhangzi bed, dating to around 122 million years ago.

<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.

<span class="mw-page-title-main">Microraptoria</span> Extinct clade of dinosaurs

Microraptoria is a clade of basal dromaeosaurid theropod dinosaurs. Definitive microraptorians lived during the Barremian to Aptian stages of the Early Cretaceous in China. Many are known for long feathers on their legs and may have been semiarboreal powered fliers, some of which were even capable of launching from the ground. Most microraptorians were relatively small; adult specimens of Microraptor range between 77–90 centimetres long (2.53–2.95 ft) and weigh up to 1 kg (2.2 lb), making them some of the smallest known non-avialan dinosaurs.

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

Rahonavis is a genus of bird-like theropod 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 dromaesaurid-like raised sickle claw on the second toe. It was originally the first African coelurosaur until the discovery of Nqwebasaurus 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. It lived during the late Campanian and early Maastrichtian stages, approximately 72 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.

Unenlagia is a genus of dromaeosaurid theropod dinosaur that lived in South America during the Late Cretaceous period. The genus Unenlagia has been assigned two species: U. comahuensis, the type species described by Novas and Puerta in 1997, and U. paynemili, described by Calvo et al. in 2004.

<span class="mw-page-title-main">Unenlagiinae</span> Extinct subfamily of dinosaurs

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, sometimes alongside the subfamily Halszkaraptorinae. Definitive members are known from South America, though some researchers include taxa from other continents within this subfamily based on phylogenetic analyses.

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

Paraves are a widespread group of theropod dinosaurs that originated in the Middle Jurassic period. In addition to the extinct dromaeosaurids, troodontids, anchiornithids, and possibly the scansoriopterygids, the group also contains the avialans, which include diverse extinct taxa as well as the over 10,000 species of living birds. Basal members of Paraves are well known for the possession of an enlarged claw on the second digit of the foot, which was held off the ground when walking in some species. A number of differing scientific interpretations of the relationships between paravian taxa exist. New fossil discoveries and analyses make the classification of Paraves an active subject of research.

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

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

Hesperonychus is a genus of small paravian theropod dinosaur. It may be a dromaeosaurid or an avialan. There is one described species, Hesperonychus elizabethae. The type species was named in honor of Dr. Elizabeth Nicholls of the Royal Tyrrell Museum of Palaeontology who collected it as a student in 1982. It is known from fossils recovered from the Dinosaur Park Formation and possibly from the uppermost strata of the Oldman Formation of Alberta, dating to the Campanian stage of the Late Cretaceous around 75 million years ago.

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

Tianyuraptor is a genus of short-armed dromaeosaurid dinosaur that lived during the Early Cretaceous, about 122 million years ago. Its remains have been found in western Liaoning, China. It was similar to other dromaeosaurids found in Liaoning, with the exception of being somewhat more primitive. The type specimen, formally named in 2009, shows features not seen in previously known Northern Hemisphere (Laurasian) dromaeosaurids, but present in Southern Hemisphere (Gondwanan) species and early birds. Because of this, the scientists who first studied Tianyuraptor described it as a "transitional species", bridging the gap between northern and southern types of dromaeosaurid. Tianyuraptor also differs from previously known dromaeosaurids in that it possesses a relatively small furcula ("wishbone"), and unusually short forelimbs.

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

Pamparaptor is an extinct genus of paravian theropod dinosaur from the Late Cretaceous Portezuelo Formation of the Neuquén province in Argentine Patagonia. Its precise classification is uncertain, but the authors who described this taxon 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".

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

This timeline of dromaeosaurid research is a chronological listing of events in the history of paleontology focused on the dromaeosaurids, a group of sickle-clawed, bird-like theropod dinosaurs including animals like Velociraptor. Since the Native Americans of Montana used the sediments of the Cloverly Formation to produce pigments, they may have encountered remains of the dromaeosaurid Deinonychus hundreds of years before these fossils came to the attention of formally trained scientists.

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

Anchiornithidae is a family of small paravian dinosaurs. Anchiornithids have been classified at varying positions in the paravian tree, with some scientists classifying them as a distinct family, a basal subfamily of Troodontidae, members of Archaeopterygidae, or an assemblage of dinosaurs that are an evolutionary grade within Avialae or Paraves.

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

Overoraptor is an extinct genus of paravian theropod of uncertain affinities from the Late Cretaceous Huincul Formation of Argentinian Patagonia. The genus contains a single species, O. chimentoi, known from several bones of the hands, feet, and hips alongside some vertebrae.

References

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