Giganotosaurus

Giganotosaurus is a genus of carnosaur from South America during the middle-cretaceous period, around ninety-one-million-years ago.

Facts
Giganotosaurus is related to the well-known Allosaurus, and therefore has carnosaur-like features, like three-fingers on their hands. They are the largest of theropods on record, dwarfing even Tyrannosaurus.

In the film
A pack of Giganotosaurus were seen in Bekon's flashback: they had tried to invade the Northern continent, but were confronted by Baku. Though they cost him an eye, Baku defeated them and driven them off single-handedly.

Trivia

 * They're nicknamed "longnecks", possibly in a nod to The Land Before Time where their sauropods are also called longnecks.