Northwestosaurus: A large theropod from Xinjiang, China

Xiongguanlong is a large theropod dinosaur from the Early Cretaceous of Gansu, China, with an estimated length of 5 meters. As a key representative of Tyrannosauroidea in Asia, it fills the evolutionary gap between small tyrannosauroid ancestors and the giant Tyrannosaurus rex. Its skull exhibits transitional features between primitive tyrannosauroids and derived tyrannosaurids. Though its size was moderate—much smaller than that of later T. rex—it already possessed the fundamental body plan characteristic of tyrannosaurs. The discovery of Xiongguanlong indicates that Tyrannosauroidea had already begun diversifying in Early Cretaceous Asia, providing crucial evidence for understanding the Asian origins and radiation of this group.