Itemirus
Encyclopedia
Itemirus is a genus of theropod dinosaur
from the Turonian
age of the Late Cretaceous
period of Uzbekistan
.
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.
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
. Nicholas Longrich and Philip Currie
in 2009 included Itemirus in a cladistic analysis of internal dromaeosaurid relationships and found it to be a velociraptorine
.
No other species have been permanently assigned to this genus. Since only the braincase was discovered, the only certain estimates concern its brain size, and evidence that it had good vision and balance, based on the large lobes of the brain.
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
age of the Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period of Uzbekistan
Uzbekistan
Uzbekistan , officially the Republic of Uzbekistan is a doubly landlocked country in Central Asia and one of the six independent Turkic states. It shares borders with Kazakhstan to the west and to the north, Kyrgyzstan and Tajikistan to the east, and Afghanistan and Turkmenistan to the south....
.
Itemirus is known from a single small damaged fossil braincase or neurocranium, in 1958 found near the village of Itemir at the Dzharakuduk escarpment
Escarpment
An escarpment is a steep slope or long cliff that occurs from erosion or faulting and separates two relatively level areas of differing elevations.-Description and variants:...
in layers of the Bissekty Formation
Bissekty Formation
The Bissekty Formation is situated in the Kyzyl Kum desert of Uzbekistan, and dates from the late Cretaceous Period. Laid down in the early the Turonian to Coniacian stages, it is dated to about 90-85 ma .The Bissekty Formation is characterised by a mix of marine, brackish, freshwater, and...
.
This holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
has accession number PIN 327/699. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, Itemirus medullaris, was named and described by Sergei Kurzanov
Sergei Kurzanov
Sergei Kurzanov is a Russian paleontologist at the Paleontological Institute of the Russian Academy of Sciences. He is known mainly for his work in Mongolia and the ex-Soviet republics in Central Asia. In 1998, a species of iguanodont dinosaur from Mongolia was named Altirhinus kurzanovi in his...
in 1976. The generic name refers to Itemir. The specific name refers to the medulla oblongata
Medulla oblongata
The medulla oblongata is the lower half of the brainstem. In discussions of neurology and similar contexts where no ambiguity will result, it is often referred to as simply the medulla...
, the brain part encased by the partial braincase.
Kurzanov noted anatomical similarities to the Tyrannosauridae
Tyrannosauridae
Tyrannosauridae is a family of coelurosaurian theropod dinosaurs which comprises two subfamilies containing up to six genera, including the eponymous Tyrannosaurus. The exact number of genera is controversial, with some experts recognizing as few as three...
and the Dromaeosauridae
Dromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...
; he assigned Itemirus to a separate Itemiridae. In 2004 Thomas Holtz suggested it was a member of the Tyrannosauroidea
Tyrannosauroidea
Tyrannosauroidea is a superfamily of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent beginning in the Jurassic Period...
. Nicholas Longrich and Philip Currie
Philip Currie
Philip Henry Wodehouse Currie, 1st Baron Currie GCB , known as Sir Philip Currie between 1885 and 1899, was a British diplomat. He was Ambassador to the Ottoman Empire from 1893 to 1898 and Ambassador to Italy from 1898 to 1902.-Background and education:Currie was the son of Raikes Currie, Member...
in 2009 included Itemirus in a cladistic analysis of internal dromaeosaurid relationships and found it to be a velociraptorine
Velociraptorinae
Velociraptorinae is a subfamily of the theropod group Dromaeosauridae. Velociraptorine remains are found mostly in northern hemisphere. In Late Cretaceous, they are mostly present in Mongolia, Romania and China,and in early, in USA. The earliest velociraptorines are probably Nuthetes from the...
.
No other species have been permanently assigned to this genus. Since only the braincase was discovered, the only certain estimates concern its brain size, and evidence that it had good vision and balance, based on the large lobes of the brain.