|An artist's rendition of Carnotaurus sastrei, quite possibly the fastest dinosaur ever|
A study of bones from this giant carnivore by undergraduate student Scott Persons from the University of Alberta, suggests a tail muscle called the caudofermoralis was connected to the thighs. It is likely that this previously unknown feature made it one of the fastest terrestrial dinosaurs on Earth. When Carnotaurus was discovered in 1985 by palaeontologist José Fernando Bonaparte, most famous for his discovery of the South American giant, Argentinosaurus huinculensis, Bonaparte noted that it possessed a strange set of rib-like structures along its tail vertebrae, each of which interlocked with the next in the line.
Using 3D computer models to reconstruct the muscular-skeletal system, Persons found that the tail ribbing would have supported an enormous caudofermoralis muscle. Secondly, its connection via tendons to the legs suggests that the two body parts would have interacted with each other, giving Carnotaurus's strides far more power, and ultimately, more speed. The theory also challenges the long-held view that the tail was there primarily to balance its powerful body and heavy head to allow it to stand or run.
The only drawback from such a system is that the tail would have been rigid, reducing the hunter's manoeuvrability. Carnotaurus would have been completely reliant on speed and power. All in all, this middle Cretaceous top predator would have had the largest caudofermoralis muscle ever and would have been one of the fastest predators of all time. While Persons has not made any calculations into its exact speed range, future studies will be able to address this.