''Ulughbegsaurus'' (meaning "

Ulugh Beg Mīrzā Muhammad Tāraghay bin Shāhrukh ( chg, میرزا محمد طارق بن شاہ رخ, fa, میرزا محمد تراغای بن شاہ رخ), better known as Ulugh Beg () (22 March 1394 – 27 October 1449), was a Timurid sultan, as ...

's lizard") is a dubious

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

aged

Bissekty Formation The Bissekty Formation (sometimes referred to as Bissekt) is a geologic formation and Lagerstätte which crops out in the Kyzyl Kum desert of Uzbekistan, and dates to the Late Cretaceous Period. Laid down in the mid to late Turonian, it is dated ...

Uzbekistan Uzbekistan (, ; uz, Ozbekiston, italic=yes / , ; russian: Узбекистан), officially the Republic of Uzbekistan ( uz, Ozbekiston Respublikasi, italic=yes / ; russian: Республика Узбекистан), is a doubly landlocked co ...

. The type species is ''Ulughbegsaurus uzbekistanensis''.

Discovery and naming

''Ulughbegsaurus'' was initially discovered within the

in the 1980s based on the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

UzSGM 11-01-02, consisting of a partial left

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

. The holotype, despite its significance, would remain in the collection of the State Geological Museum of the State Committee of the Republic of Uzbekistan on Geology and Mineral Resources,

Tashkent Tashkent (, uz, Toshkent, Тошкент/, ) (from russian: Ташкент), or Toshkent (; ), also historically known as Chach is the capital and largest city of Uzbekistan. It is the most populous city in Central Asia, with a population of 2 ...

, until 2019, when it was rediscovered. Two additional referred specimens have been attributed to the genus, including CCMGE 600/12457, an

jugal The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anatomy ...

ramus of a left maxilla that was previously referred to the

dromaeosaurid Dromaeosauridae () is a family of feathered 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 ('), meaning ...

Itemirus ''Itemirus'' is a genus of dromaeosaurid theropod dinosaur from the Turonian age of the Late Cretaceous period of Uzbekistan. Discovery ''Itemirus'' is known from a single small damaged fossil braincase or neurocranium, in 1958 found near the ...

'' and ZIN PH 357/16, the posterior end of a right maxilla. Isolated

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...

from the Bissekty Formation show similarities with

carcharodontosaurian Allosauroidea is a superfamily or clade of theropod dinosaurs which contains four families — the Metriacanthosauridae, Allosauridae, Carcharodontosauridae, and Neovenatoridae. Allosauroids, alongside the family Megalosauroidea, were among th ...

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

, suggesting they may belong to ''Ulughbegsaurus'' or possibly another genus of carcharodontosaurian. The genus and

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

was later named in 2021 by Tanaka et al., honouring the 15th century Timurid sultan and scientist Ulugh Beg and the country of its discovery.

Description

The body length of ''Ulughbegsaurus'' is estimated at and its body mass at over .

Classification

Tanaka ''et al.'' ran two phylogenetic analyses using two different datasets to determine the relationships of ''Ulughbegsaurus''. The first placed it in a

polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...

including ''

Neovenator ''Neovenator'' (nee-o-ven-a-tor meaning "new hunter") is a genus of carcharodontosaurian theropod dinosaur. It is known from several skeletons found in the Early Cretaceous (Barremian~130-125 million years ago) Wessex Formation on the south coa ...

'' and other

megaraptoran Megaraptora is a clade of carnivorous tetanuran theropod dinosaurs with controversial relations to other theropods. Its derived members, the Megaraptoridae are noted for their elongated hand claws and proportionally large arms, which are usually ...

s, while the second placed it in a polytomy including other basal carcharodontosaurians; megaraptorans were instead recovered as members of the

Tyrannosauroidea Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinen ...

. Both analyses are shown below: Topology 1: Hendrickx & Mateus dataset Topology 2: Chokchaloemwong ''et al.'' dataset However, a later 2022 study suggested that the taxon was a ''nomen dubium'' due to lacking diagnostic features, and that it was plausible that the maxilla fragment originated from a

instead.

Paleobiology

''Ulughbegsaurus'' coexisted in the

environment alongside other carnivorous theropods, including the tyrannosauroid ''

Timurlengia ''Timurlengia'' is an extinct genus of tyrannosauroid theropod dinosaur found in Uzbekistan, in the Bissekty Formation in the Kyzylkum Desert, hailing from the Turonian age of the early Late Cretaceous. The type species is ''Timurlengia euotica'' ...

'' and the dromaeosaurid ''

''.

References

Bissekty Formation Prehistoric tetanurans Turonian life Late Cretaceous dinosaurs of Asia Fossil taxa described in 2021 Nomina dubia {{theropod-stub