Sinotyrannus is a genus of possible proceratosaurid tyrannosaur. Despite being not much younger than Dilong, another basal tyrannosaur, Sinotyrannus was very large in size, closer to that of Tyrannosaurus than Dilong.. It was 10 meters (33 feet) long and lived in the early part of the Cretaceous period, approximately 120 million years ago.
It was a basal tyrannosauroid and was the top predator at it's time in it's environment, the Jihol Biota.
Fossils can be found in the Jiufotang Formation along with other animals such as the dinosaurs Microraptor , Longipteryx, Jeholornis, Yanornis and the pterosaur Liaoxipterus.