Giganotosaurus (meaning "giant southern lizard") is a genus of theropod that lived in Argentina during the Late Cretaceous period. It is currently one of the largest known meat-eating dinosaurs and the largest allosaurid to ever exist. For many years Tyrannosaurus held that record, although bits and pieces of Carcharodontosaurus and Spinosaurus showed that they possibly could rival the giant coelurosaur in size. Then, in the late 1980s into the early 1990s, Argentine paleontologists Rodolfo Coria and Leonardo Salgado discovered and revealed the existence of a new meat-eater bigger than any known tyrant lizard. They named the giant dinosaur Giganotosaurus carolini. While determining exactly which theropod genera was the largest, metrics for Giganotosaurus have consistently placed it as larger than an average Tyrannosaurus rex and comparable to the largest known specimens of the Tyrant Reptile King. More specimens of the Giant Southern Reptile are required to give a clearer picture of size, as all species will exist within a spectrum of sizes. For now it is safest to consider the likes of Giganotosaurus, Spinosaurus, and Tyrannosaurus as comparable to one another in terms of size (though Spinosaurus is technically the longer animal at 50 feet, it is comparable in weight to Tyrannosaurus and Giganotosaurus due to its more slender build in real life). When Giganotosaurus was alive, the most common herbivores found in South America were the titanosaur sauropods such as Argentinosaurus, Dreadnoughtus, and Andesaurus, respectively. While a single Giganotosaurus was capable of killing a young titanosaur or a large ornithopod, it would take many Giganotosaurus to bring down a giant adult sauropod. Originally, there was no evidence that Giganotosaurus hunted in groups, but recent findings from slightly younger rocks shows that their sister taxon (closest relative) Mapusaurus may have formed coalitions similar to crocodiles or perhaps even family groups given the high size variation and age differences between individuals. While not known if this was true pack living behavior, these coalitions of 6 or more individuals would probably have been capable of coordinating attacks on targets of opportunity such as a large sauropod.