Yangchuanosaurus is a genus of theropod dinosaur from the Oxfordian (and possibly Kimmeridgian) stage of the Late Jurassic Period, and comes from the Upper Shaximiao Formation. A nearly complete skeleton was discovered in June 1977 by a construction worker during the building of the Shangyou Reservoir Dam in the Yongchuan District.
This genus was considered the same as Metriacanthosaurus by Gregory S. Paul in 1988, but this has not received the support of other paleontologists.
The type species of Y. shangyouensis is on display at the Municipal Museum of Chongqing along with some material from Y. magnus. A fossil found in Sichuan, Xuanhan County is on display at the Beijing Museum of Natural History. A cast skeleton of the type species is also on display at Dinopolis, in Spain.
Yangchuanosaurus was a relatively large theropod. The type specimen has a skull of 2.7 feet long. Its total body length is estimated to have been about 26 feet long. Y. magnus was even larger, with a skull length of 3.6 feet. It may have been up to 35 feet long, and weighed as much as 3.7 tons. Its massive tail was about half its total length.
Yangchuanosaurus was similar in size and appearance to its North American contemporary, Allosaurus. It was the largest predator in the region during its reign.