Giganotosaurus is a dinosaur that lived about 100 to 90 million years past during the mid Cretaceous time and is measured to be the heaviest known terrestrial carnivore.

About 70 percent of the holotype specimen's (MUCPv-Ch1) skeleton was improved by paleontologists, including the skull, pelvis, leg bones, and most of the backbone. An eight percent longer specimen (MUCPv-95) also has been improved. The largest Giganotosaurus specimen is predictable to be 14.3 m (47 ft) in length and weigh up to 8,000 kg (9 tons), surpassing Tyrannosaurus rex by almost 2 m and 2,000 kg (6.5 ft and 2.2 tons). The specimen’s skull alone measures 1.95 m (6 ft 5 in).

Though longer and heavier than T. rex, G. carolinii was moderately slender and had a smaller braincase in comparison. However, even although the brain of Giganotosaurus was the size of a banana, a well-developed olfactory region indicates that it may have had a good intellect of smell.

Titanosaurid fossils have been improved near the remains of Giganotosaurus, leading to speculation that these carnivores may have preyed on the giant herbivores.

G. carolinii was named for Ruben Carolini, an amateur fossil hunter who exposed the fossils in the deposits of the Rio Limay Formation of Patagonia, in 1993. The genus name "Giganotosaurus" is consequent from the Greek gigas ("giant"), notos ("south wind") and sauros ("lizard"). Both names were published by Rodolfo Coria and Leonardo Salgado in the periodical Nature in 1995. The original fossils stay at the Carmen Funes Museum in Neuquen, Argentina, although replicas are commonly established in other places. The family of Giganotosaurus and Carcharodontosaurus is in fact Carcharodontosauridae.