Kelmayisaurus is a genus of carcharodontosaurid theropod dinosaur from the early Cretaceous. It was roughly 9-11 meters (30-36 feet) Its name refers to the petroleum-producing city of Karamay in the Xinjiang province of western China near where it was found.
Kelmayisaurus is known from the holotype and only specimen IVPP V 4022. It consists of a complete left dentary (lower jaw with teeth) and partial left maxilla. The specimen was found in the Lianmugin Formation of the Tugulu Group, dating to the Valanginian-Albian stages, around 140 to 100 million years ago. The discovery locality is near Wuerho in the Junggar Basin. It was first named and described by Chinese paleontologist Dong Zhiming in 1973 and the type species is Kelmayisaurus petrolicus. A supposed second species, K. “gigantus”, was mentioned by Grady in a children book in 1993 as a gigantic vertebral column coming from a 22 m long specimen, but is a nomen nudum and probably does not pertain to Kelmayisaurus. It may be a sauropod instead.
Kelmayisaurus has been thought to be a nomen dubium due to its scanty remains, and its phylogenetic position was uncertain. It has usually been regarded as a basal tetanuran of uncertain affinities. However, Kelmayisaurus is diagnosable by the form and presence of a deeply inset accessory groove on the lateral side of the dentary, the main toothbearing bone of the lower jaw. Some of its features are like those of carcharodontosaurians, but they are also seen in large megalosauroids like Megalosaurus and Torvosaurus.
In 2011, a redescription of the holotype by Stephen L. Brusatte, Roger B. J. Benson and Xing Xu found Kelmayisaurus to be valid genus of Carcharodontosauridae with a single autapomorphy. A phylogenetic analysis of Tetanurae recovered K. petrolicus as a basal carcharodontosaurid in a trichotomy with Eocarcharia and a clade comprising more derived carcharodontosaurids.