Kostensuchus atrox was not a dinosaur, but a peirosaurid crocodyliform, an extinct group of reptiles related to modern crocodiles and alligators.
Using the fossilised remains, scientists were able to work out that the crocodile relative reached around 3.5 metres in length and had huge powerful jaws that could tackle medium-sized dinosaurs.
Fernando Novas, a paleontologist at the National Scientific and Technical Research Council in Argentina, concluded that as well as powerful jaws, the creature had robust limbs that were longer than crocodile legs today, possibly to subdue large prey.
While we often think of dinosaurs as being the top predators of the time, it is interesting to see that there were other creatures which hunted them.