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Yangchuanosaurus is an extinct genus of carnivorous metriacanthosaurid allosauroid that lived in China from the Middle to Late Jurassic periods (Bathonian to Oxfordian, about 168 to 157 mya), and was similar in size and appearance to its more famous relative, Allosaurus. Yangchuanosaurus hails from the rocks of the Upper Shaximiao Formation. This theropod was named after the area in which was discovered, Yongchuan, in China.
The subadult type specimen of Y. shangyouensis had a skull length of 78 cm, a femur length of 85 cm, and an estimated total length of 8.6 meters. The paratype was even larger, with an estimated skull length of 111 cm, a femur length of 95 cm, an estimated length of 10.2 meters, and an estimated weight of 2500 kg. A referred femur with a length of 120 cm suggests larger sizes still, possibly up to 12.9 meters and 5000 kg. This is similar in size to modern rhinos and elephants and puts Yangchuanosaurus among the largest known theropods of the Jurassic.
The skull of Yangchuanosaurus was large, deep, and broad, housing numerous sharp and serrated teeth. The neural spines of the torso were moderately tall, perhaps serving as muscle attachments. The hindlimbs were short and stout, possibly related to locomotion in forests. Yangchuanosaurus probably fed on the contemporary sauropods Mamenchisaurus and Omeisaurus as well as the stegosaurs Chialingosaurus, Tuojiangosaurus and Chungkingosaurus. Being the largest known carnivorous animal from the rock formations it was found, it may have been the apex predator.