Artiosaurus

Artiosaurus is an extinct genus of sauropodomorph that lived in what is now North America during the Late Jurassic, and is among the last of the prosauropods. Artiosaurus is only known in one species, A. glatisantus, which grew to be nearly as big as the carcharodontosaurs of Cretaceous Africa and South America, and due to its size, it is debatable whether or not it was really bipedal or semi-bipedal. Unlike any other advanced prosauropods, which were all completely or nearly completely herbivorous, Artiosaurus has evolved on a completely different route, by evolving to be carnivorous (or, at least, mostly carnivorous), becoming a sort of dinosaurian equivalent to bears. Due to its large size and possibly its aggression, it was most likely able to scare off almost all theropods (even the famous Allosaurus), to steal the kills of other carnivores, but if the theropod doesn't back down and leave its kill, Artiosaurus would use its long claws to intimidate or injure its rival, likely fatal. It is unknown on why Artiosaurus had became extinct at the end of the Jurassic, but it may have been due to climate change, competition from newly-evolved scavengers like Saurophaganax, or even both.