Sinotyrannus

Sinotyrannus (meaning "Chinese tyrant") is an extinct genus of large tyrannosauroid theropod dinosaurs known from the Early Cretaceous Jiufotang Formation of Liaoning, China. This genus contains a single species, Sinotyrannus kazuoensis, known from a single mature specimen including a partial skull, some vertebrae, and part of the pelvic girdle.

While it exhibited greater body size that would put it on par with the later tyrannosaurids such as Tyrannosaurus (a group that Sinotyrannus was initially suspected of being in), Sinotyrannus was more likely a member of the family Proceratosauridae, basal within or closely related to tyrannosauroids. This family originated in the Jurassic, and its members are known from Europe and Asia. Sinotyrannus and its coeval relative Yutyrannus appear to have been surprisingly large compared to most of their Early Cretaceous relatives, such as Dilong. Most of the world during the Early Cretaceous was dominated by more basal tetanurans, such as the megalosauroids and allosaurs, with tyrannosaurids themselves only taking over after both groups started to decline. However, Sinotyrannus and Yutyrannus appear to be exceptions to this.

Sinotyrannus was the largest theropod in the Jiufotang Formation, reaching up to 10 metres (33 ft) in length. The smaller theropod Huaxiagnathus from the older Yixian Formation, traditionally regarded as a "compsognathid" and known only from immature specimens, may be an immature form of Sinotyrannus. If this hypothesis is supported, Sinotyrannus would be a junior synonym of Huaxiagnathus.