The Yangchuan Lizard's Profile

A lot of characteristics come together here

Yangchuanosaurus has a skull open to interpretation, let us start off by saying that. The ridges and bumps on the top of the nasal, frontal, and parietal bones in particular have evoked ideas of similarities between this animal and Ceratosaurus while simultaneously evoking images of the brow ridges of Allosaurus and its closest relatives. The snout itself is not elongated but somewhat stubbed, like that of Carnotaurus rather than either Ceratosaurus or Allosaurus, however, its body form is much more like that of Allosaurus than either Carnotaurus or Ceratosaurus. Yangchuanosaurus is somewhat of an enigma thanks to all of these slight similarities. However, unlike all of these previously noted similarities, it seems to also possess high vertebral spines, in one mounted skeleton at any rate,

No high spines here

compared to these animals which evokes more of an Acrocanthosaurus type image, further enhancing our enigma. In the end it is an entirely unique animal which has characteristics from all over that had either evolved already or were evolving throughout the development of this genus. What we have is a member of the sinraptoridae which is obviously related to allosaurs and later animals but took its own course at the same time. It is a truly interesting animal as it was well developed for its niche in the Chinese environment in which it lived, taking the position in the niche which Allosaurus, rather than Ceratosaurus, held contemporaneously in North America. This was certainly an animal at home with attacking stegosaurs and sauropods and, like Allosaurus, most likely hunted in packs when it needed to if not always.

©Mark Hallett

This illustration goes for exactly what I was just saying. Actually, this is only a pair as far as we can tell from this exact image in the scene, but it is quite clear that they are working on isolating a sauropod, which is certainly not Mamenchisaurus given the neck length shown here, from its herd. Not that the sauropod, Shunosaurus, has a tail club with a few spikes represented on it. That sort of hunting environment, where the sauropods as well as the stegosaurus wielded clubs must mean that Yangchuanosaurus must have been quite a robust animal to survive. I have not seen any braincase studies but looking at the prey items available I feel it is safe to say that Yangchuanosaurus more than likely had a solid skull and that its bones were heavy things able to withstand some of the punishment its prey could dish out. If they were not, this would not have been a very successful animal. It does certainly have the teeth and claws needed for inflicting grave injury, but to get in that close it would have needed both speed and the ability to absorb a punch to the face. I have a feeling that we are going to find this animal to be quite a prize fighter.

The general consensus with illustrations appears to give Yangchuanosaurus bumps and ridges more like a Ceratosaurus than the prominent sustained brow ridges of Allosaurus. Either way I am okay with this because I think a little bit of raggedness to the silhouette of a dinosaur is fairly awe inspiring and makes it look much more like a real animal. Imperfections and individual bumps and ridges which can identify an individual are, after all, hallmarks of most living animals today across the spectrum. Though we generally do not see differences in one ant as opposed to another, say, they are there and they make them what they are, and that is quite interesting. Therefore, I think rather that the ridges and bumps found on the skulls of Yangchuanosaurus are probably highly distinct and because of that they can be illustrated any number of ways in order to show this individuality.