Itemirus

Itemirus is a genus of theropod dinosaur from the Turonian age of the Late Cretaceous period of Uzbekistan.

Itemirus
Temporal range: Late Cretaceous, 91 Ma
Itemirus medullaris
Rear of skull
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Dromaeosauridae
Clade: Eudromaeosauria
Subfamily: Dromaeosaurinae
Genus: Itemirus
Kurzanov, 1976
Species:
I. medullaris
Binomial name
Itemirus medullaris
Kurzanov, 1976

Discovery

Itemirus is known from a single small damaged fossil braincase or neurocranium, in 1958 found near the village of Itemir at the Dzharakuduk escarpment in layers of the Bissekty Formation. This holotype has accession number PIN 327/699. The type species, Itemirus medullaris, was named and described by Sergei Kurzanov in 1976. The generic name refers to Itemir. The specific name refers to the medulla oblongata, the brain part encased by the partial braincase.[1]

Classification

Kurzanov noted anatomical similarities to the Tyrannosauridae and the Dromaeosauridae; he assigned Itemirus to a separate Itemiridae. In 2004 Thomas Holtz suggested it was a member of the Tyrannosauroidea.[2] Nicholas Longrich and Philip J. Currie in 2009 included Itemirus in a cladistic analysis of internal dromaeosaurid relationships and found it to be a velociraptorine.[3] In 2014, during a study assigning more material to Itemirus, it was found that the genus could be placed in Dromaeosaurinae in a phylogeny.[4]

Eudromaeosauria

Bambiraptor

Saurornitholestes

Velociraptorinae

Deinonychus

Adasaurus

Velociraptor

Balaur

Dromaeosaurinae

Tsaagan

Dromaeosaurus

Atrociraptor

Utahraptor

Achillobator

Itemirus

See also

References

  1. ^ Kurzanov, S. M. (1976) Braincase structure in the carnosaur Itemirus n. gen. and some aspects of the cranial anatomy of dinosaurs. Paleontological Journal 10:361-369.
  2. ^ Holtz, T.R., 2004, "Tyrannosauroidea". In: D. B. Weishampel, P. Dodson, and H. Osmolska (eds.), The Dinosauria (second edition). University of California Press, Berkeley pp. 111-136
  3. ^ Longrich, N.R. and Currie, P.J. (2009). "A microraptorine (Dinosauria–Dromaeosauridae) from the Late Cretaceous of North America." Proceedings of the National Academy of Sciences 106(13): 5002–5007. doi: 10.1073/pnas.0811664106
  4. ^ Sues, H.-D.; Averianov, A. (2014). "Dromaeosauridae (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan and the phylogenetic position of Itemirus medullaris Kurzanov, 1976". Cretaceous Research. 51: 225–240. doi:10.1016/j.cretres.2014.06.007.
Acheroraptor

Acheroraptor is an extinct genus of dromaeosaurid theropod dinosaur known from the latest Maastrichtian Hell Creek Formation of Montana, United States. It contains a single species, Acheroraptor temertyorum. A. temertyorum is one of the two geologically youngest known species of dromaeosaurids, the other being Dakotaraptor, which is also known from Hell Creek.

Dromaeosaurinae

Dromaeosaurinae is a subfamily of Dromaeosauridae. Most dromaeosaurines lived in what is now the United States and Canada, as well as Mongolia, and possibly Denmark as well. Isolated teeth that may belong to African dromaeosaurines have also been discovered in Ethiopia. These teeth date to the Tithonian stage, of the Late Jurassic Period.All North American and Asian dromaeosaurine dinosaurs from the Late Cretaceous were generally small, no more than 1.8 metres (5.9 ft) long, in Dromaeosaurus and Adasaurus. However, among the dromaeosaurines were the largest dromaeosaurs ever; Dakotaraptor was ~5.5 metres (18 ft) long, Achillobator 6 metres (20 ft), and Utahraptor up to ~7 metres (23 ft).

Eudromaeosauria

Eudromaeosauria ("true dromaeosaurs") is a subgroup of terrestrial dromaeosaurid theropod dinosaurs. They were relatively large-bodied, feathered hypercarnivores (with diets consisting almost entirely of other terrestrial vertebrates) that flourished in the Cretaceous Period.

Eudromaeosaur fossils are known almost exclusively from the northern hemisphere. They first appeared in the early Cretaceous Period (early Aptian stage, about 124 million years ago) and survived until the end of the Cretaceous (Maastrichtian stage, 66 Ma). The earliest known definitive eudromaeosaur is the dromaeosaurine Utahraptor ostrommaysorum, from the Cedar Mountain Formation, dated to 124 million years ago. However, the earlier (143-million-year-old) fossils such as those of Nuthetes destructor and several indeterminate teeth dating to the Kimmeridgian stage may represent eudromaeosaurs.

Graciliraptor

Graciliraptor (meaning "graceful thief") is a genus of theropod dinosaur from the early Cretaceous Period. It is a microraptorine dromaeosaurid.

The type species Graciliraptor lujiatunensis was first named and described in 2004 by Xu Xing and Wang Xiaoling. The generic name is derived from Latin gracilis and raptor. The specific name refers to the village Lujiatun where the fossil site is located. Its fossil, holotype IVPP V 13474, was found in Beipiao, Liaoning Province, China.

Halszkaraptorinae

Halszkaraptorinae is a basal ("primitive") subfamily of Dromaeosauridae that includes the enigmatic genera Halszkaraptor, Mahakala, and Hulsanpes. A comparison of the fossils of Halszkaraptor with the bones of extant crocodilians and aquatic birds revealed evidence of a semiaquatic lifestyle. The group is named after Polish paleontologist Halszka Osmólska.

Hulsanpes

Hulsanpes is a genus of dromaeosaurid theropod dinosaur from Mongolia that lived during the Late Cretaceous.

Linheraptor

Linheraptor is a genus of dromaeosaurid dinosaur which lived in what is now China in the Late Cretaceous. It was named by Xu Xing and colleagues in 2010, and contains the species Linheraptor exquisitus. This bird-like dinosaur was less than 2 m (6.5 ft) long and was found in Inner Mongolia. It is known from a single, nearly complete skeleton.

Luanchuanraptor

Luanchuanraptor (meaning "Luanchuan thief") is a genus of dromaeosaurid theropod dinosaur from the Late Cretaceous of China. It is based on a partial skeleton from the Qiupa Formation in Luanchuan, Henan. A medium-sized dromaeosaurid, it is the first Asian dromaeosaurid described from outside the Gobi Desert or northeastern China. The fossil material is cataloged as 4HIII-0100 in the Henan Geological Museum and includes four teeth, one frontal, a neck vertebra, one or two back vertebrae, seventeen tail vertebrae, ribs, chevrons, a humerus (upper arm bone), claw and finger bones, partial shoulder and pelvic girdles, and other fragmentary bones from a moderately sized dromaeosaurid. The type species is L. henanensis, described by Lü et al. in 2007.

Neuquenraptor

Neuquenraptor is a genus of dromaeosaurid theropod dinosaurs of the Late Cretaceous of Argentina, one of the first dromaeosaurids found in the Southern Hemisphere.

Pamparaptor

Pamparaptor is an extinct genus of carnivorous deinonychosaur from the late Cretaceous period. It is a basal dromaeosaurid dinosaur with troodontid-like pes which lived during the late Cretaceous period (Turonian to Coniacian stage) in what is now Neuquén province, Patagonia, Argentina. It is known from the holotype MUCPv-1163, an articulated and nearly complete left foot.

The specimen recovered from the Portezuelo Formation (Río Neuquén Subgroup) of Neuquén Group. It was initially considered to be a juvenile specimen of another dromaeosaurid species, Neuquenraptor argentinus. However, it was later re-interpreted as a new genus and named Pamparaptor by Juan D. Porfiri, Jorge O. Calvo and Domenica dos Santos in 2011 and the type species is Pamparaptor micros. The generic name honors Indian Pampas people who lived in central Argentina while "raptor" (robber in Latin). The specific name (micros, meaning "small") refers to the specimen's size (estimated at 0.5 to 0.7 metres (1.6 to 2.3 ft) in length).

Pyroraptor

Pyroraptor (meaning "fire thief") is a genus of dromaeosaurid dinosaur from the Late Cretaceous of what is now southern France, it lived during the late Campanian and early Maastrichtian stages, approximately 70.6 million years ago. It is known from a single partial specimen that was found in Provence in 1992. The animal was named Pyroraptor olympius by Allain and Taquet in 2000.

Saurornitholestinae

Saurornitholestinae is a subfamily of dromaeosaurid dinosaurs. The saurornitholestines currently include three monotypic genera: Atrociraptor marshalli, Bambiraptor feinbergorum, and Saurornitholestes langstoni. All are medium-sized dromaeosaurs from the Late Cretaceous of western North America. The group was originally recognized by Longrich and Currie as the sister taxon to a clade formed by the Dromaeosaurinae and Velociraptorinae. However, not all phylogenetic analyses recover this group.

Shanag

Shanag is a genus of dromaeosaurid theropod dinosaur from the Early Cretaceous Period of Mongolia.

The type species of Shanag is S. ashile. It 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.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. The holotype specimen, about six centimetres 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.Shanag was a small predator. In 2010 Gregory S. Paul estimated its length at 1.5 metres, the weight at five kilogrammes. Shanag shows a mixture of dromaeosaurid, troodontid and basal avialan traits.Turner et alii assigned Shanag to the Dromaeosauridae. Their cladistic analysis indicated that it was a basal dromaeosaurid but higher in the tree than the Unenlagiinae. Later analyses recovered it in the Microraptorinae.

Unenlagiinae

Unenlagiinae is a subfamily of dromaeosaurid theropods. Unenlagiines are known from South America and Antarctica.

Unquillosaurus

Unquillosaurus (meaning "Unquillo river lizard") is a genus of maniraptoran dinosaur from the Late Cretaceous Period, discovered in Argentina. Known only from a single fossilized pubis (a pelvic bone), its total body length may have reached 2 to 3 metres (6.6 to 9.8 ft).

Variraptor

Variraptor ( VARR-i-rap-tor; "Var thief") is a genus of coelurosaurian theropod dinosaur from the Late Cretaceous of France.

Velociraptorinae

Velociraptorinae is a subfamily of the theropod group Dromaeosauridae. The earliest velociraptorines are probably Nuthetes from the United Kingdom, and possibly Deinonychus from North America. However, several indeterminate velociraptorines have also been discovered, dating to the Kimmeridgian stage, in the Late Jurassic Period. These fossils were discovered in the Langenberg quarry, Oker near Goslar, Germany.In 2007 paleontologists studied front limb bones of Velociraptor and discovered small bumps on the surface, known as quill knobs. The same feature is present in some bird bones, and represents the attachment point for strong secondary wing feathers. This finding provided the first direct evidence that velociraptorines, like all other maniraptorans, had feathers.While most velociraptorines were generally small animals, at least one species may have achieved gigantic sizes comparable to those found among the dromaeosaurines. So far, this unnamed giant velociraptorine is known only from isolated teeth found on the Isle of Wight, England. The teeth belong to an animal the size of dromaeosaurines of the genus Utahraptor, but they appear to belong to a velociraptorine, judging by the shape of the teeth and the anatomy of their serrations.

Yurgovuchia

Yurgovuchia is an extinct genus of dromaeosaurid theropod dinosaur known from the Early Cretaceous (probably Barremian stage) of Utah. It contains a single species, Yurgovuchia doellingi. According to a phylogenetic analysis performed by its describers, it represents an advanced dromaeosaurine, closely related to Achillobator, Dromaeosaurus and Utahraptor.

Zhongjianosaurus

Zhongjianosaurus is a genus of dromaeosaurid belonging to the Microraptoria. Believed to hail from the Yixian Formation, specifically the middle of the Jehol Biota, it is the smallest known microraptorine thus far discovered and one of the smallest non-avian theropod dinosaurs.

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