Creature of the Week # 25: Yangchuanosaurus

Yangchuanosaurus was a large theropod dinosaur which lived in China during the late Jurassic. It is often, somewhat unfairly, referred to as the Chinese Allosaurus. While the two animals are certainly closely related and share many similarities, Yangchuonosaurus has several key features which make it stand out. Facially speaking, Yangchuanosaurus at a glance probably looked more like a ceratosaur than your average allosaur. Like Ceratosaurus it had a horn of sorts on it's snout as well as all manner of bumps and ridges.

See?

Interestingly, Yangchuanosaurus seems to have some sort of hump on it's back, leading palaeontologist Gregory S. Paul to question whether Yangchuanosaurus was a valid genus or whether it was in fact one in the same as Metriacanthosaurus (of Jurassic Park 'fame'), the so called 'moderately spined lizard'. It has also been suggested that Yangchuanosaurus may have resembled the oddly humped carcharodontosaur Concavenator.

"We're not so different you and I..."

Yangchuanosaurus shared it's habitat with a variety of dinosaurs such as long necked sauropods (including the gigantic Mamenchisaurus, which is now believed to be one of the largest dinosaurs of all time) and stegosaurs such as the very spiky Tuojiangosaurus.
There are two known species of Yangchuanosaurus; Y. shangyouensis which was about 8 meters long and the mighty Y. magnus which was almost 11 meters in lenght and weighed almost 4 tons, rivaling the biggest Allosaurus specimens in terms of size. It has been speculated that the two species were specialized in dealing with different prey items; shangyouensis may have hunted the stegosaurs while magnus was equipped to hunt sauropods.
Curiously this set up, to an extent, mirrors that of the famous Morrison formation of late Jurassic North America where Allosaurus would be considered the big game hunter, while the smaller Ceratosaurus combated with stegosaurs. With the absence of Ceratosaurus in China the species Yangchuanosaurus shangyouensisappears to have occupied the same niche in a similar eco system.

Ceratosaurus takes on Stegosaurus: Yangchuanosaurus may have had similar battles with Asian stegosaurs.