[1] This dinosaur had a single type species, S. kazuoensis, with the only known specimen containing a partial skull, some vertebrae, and a hip,[2] all of which were found in the Early Cretaceous aged Jiufotang Formation of Liaoning, China.

Most of the world during the Early Cretaceous was dominated by more basal tetanurans, such as the megalosaurs and allosaurs, with tyrannosaurids themselves only taking over after both groups started to decline.

Sinotyrannus was the largest theropod in the Jiufotang Formation, reaching up to 10 meters (32.8 ft) in overall length and having a general mass similar to that of a large rhino.

[2] The original description of Sinotyrannus proposed that it could have been the earliest tyrannosaurid due to its large size,[2] but subsequent analyses place it as a proceratosaurid tyrannosauroid.

A 2013 study by Loewen et al. considered it to be part of a clade containing Juratyrant and Stokesosaurus, as they all reputedly share a narrow preacetabular notch.

The results of their phylogenetic analyses are shown in the cladogram below:[7] Proceratosaurus bradleyi Kileskus aristotocus Guanlong wucaii Sinotyrannus kazuoensis Juratyrant langhami Stokesosaurus clevelandi Dilong paradoxus Eotyrannus lengi Bagaraatan ostromi Raptorex kriegsteini Dryptosaurus aquilunguis Alectrosaurus olseni Xiongguanlong baimoensis Appalachiosaurus montgomeriensis Alioramus altai Alioramus remotus Tyrannosauridae However, Brusatte et al. (2016) instead placed Juratyrant and Stokesosaurus outside of the Proceratosauridae, and proposed that Sinotyrannus represents the sister taxon of Yutyrannus within Proceratosauridae.