Giganotosaurus is the second largest known Theropod. It was 15 metres long, 6 metres tall and weighed 7-8 tonnes. Giganotosaurus, means, 'Giant Southern Lizard'. Only Spinosaurus is larger, at a maximum of 16-18 metres long and perhaps 9 tonnes. Allosaurus and other Allosaurids were close relatives.
It is somewhat erroneously referred to by Nigel Marven as the biggest land predator of all time - an honour which currently belongs to the two 56-60 foot Spinosaurus subspecies, Spinosaurus aeygptiacus and Spinosaurus maroccanus. Nevertheless, Giganotosaurus carolinii would still be the second largest land carnivore ever, with by comparison the huge Tyrannosaurus rex relegated to 4th biggest.