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 probably a member of the basal tyrannosauroid family known as the Proceratosauridae. This family originated in the Jurassic, whose members are known from Europe and Asia. Sinotyrannus and its close relative Yutyrannus appear to have been surprisingly large compared to most tyrannosauroids of the Early Cretaceous, 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.