Ulughbegsaurus

As a carcharodontosaur.

*Ulughbegsaurus* is a dubious genus of theropod dinosaur that lived in Uzbekistan during the Late Cretaceous.

## History

The holotype, UzSGM 11-01-02 was discovered by a field team led by Lev Alexandrovich Nessov in the Bissekty formation, located in the Kyzylkum Desert of Navoi, Northern Uzbekistan. It consists of an isolated left maxilla, housed at the State Geological Museum of Uzbekistan in Tashkent. The new genus *Ulughbegsaurus* was named in September 2021 by Kohei Tanaka and coauthors, who also referred two other specimens to the genus. CCMGE 600/12457 is a partial left maxilla, and ZIN PH 357/16, a right maxilla previously identified as belonging to *Itemirus*, a dromaeosaur, and newly classified as a carcharodontosaurian. Press articles from around the time of initial publication state *Ulughbegsaurus* (misspelled "*Ulughbegasaurus*" by one article) was 5x larger than and fed upon *Tyrannosaurus*; this is a mistake, as *Ulughbegsaurus* was much smaller than *Tyrannosaurus*, lived at a different time and in a different place and did not feed on it. Instead, *Ulughbegsaurus* was larger than contemporaneous tyrannosaurs and may have fed on them, which is indicated than the description paper, contrary to what was publicized. A 2022 paper may suggest that a dromaeosaur identification was right and that the holotype has the potential to represent a large dromaeosaurid rather than a carcharodontosaur. Instead, they call it a dubious genus.

## Description

 File:Ulughbegsaurus uzbekistanensis.png
It is the largest predatory dinosaur of the Bissekty formation, which was deposited 90-92 million years ago. It was probably the apex predator of its ecosystem, which also included Sauropods, Birds, small Tyrannosaurs, and Dromaeosaurs (raptors). The dinosaur is named after the 15th century Sultan Ulugh Beg with the suffix -saurus meaning "reptile". The type and only species is *Ulughbegsaurus uzbekistanensis* named after the Republic of Uzbekistan where it was discovered. The holotype is nondiagnostic to carcharodontosaurians.

## Classification

The authors used several datasets to recover multiple cladograms. With Hendrickx & Mateus' dataset, which suggests a carcharodontosaurian affinity:

Chokchaloemwong et al.'s dataset:

Sues, Averianov and Britt (2022) reason that the identification of large dromaeosaurs in the Bissekty, such as a pedal phalanx II-2, and the nondiagnostic of the *U. uzbekistanensis* holotype may cement this taxon as a member of Dromaeosauridae rather than a Carcharodontosauria.

## Notable Specimens

* UzSGM 11-01-02: A left maxilla; the holotype.
* CCMGE 600/12457 and ZIN PH 357/16 "The Big One": A jugal ramus of the left maxilla and the posterior end of the right maxilla, respectively, once referred to *Itemirus*[*citation needed*].

## References

1. ↑ https://news.yahoo.com/researchers-identify-dinosaur-species-5-182121345.html
2. ↑ 2.0 2.1 2.2 https://www.cambridge.org/core/journals/geological-magazine/article/abs/giant-dromaeosaurid-theropod-from-the-upper-cretaceous-turonian-bissekty-formation-of-uzbekistan-and-the-status-of-ulughbegsaurus-uzbekistanensis/4543ABAB1EC19C84405EDF66A5F53124
3. ↑ https://royalsocietypublishing.org/doi/10.1098/rsos.210923