Giganotosaurus

Credit: R.J. Palmer.

*Giganotosaurus* is a genus of large carcharodontosaurid theropod dinosaur that lived during the Late Cretaceous in Argentina.

## Description

*Giganotosaurus* is the third or fourth largest predatory theropod dinosaur known, and assumed to being capable of hunting some of the largest sauropods in small groups. Giganotosaurus is the most popular member of Carcharodontosauridae along with *Carcharodontosaurus*. *Giganotosaurus* has two large bony brow ridges above its eyes, likely for sexual orientation.

*Giganotosaurus* has a slim build (in comparison to tyrannosaurids like *Tyrannosaurus*), built off of a large body; the carnivore had long, strong legs, robust forelimbs with large hooked claws, a long muscular tail and cutting jaws topped by a pair of sagittal crests. Giganotosaurus is thought to be the 4rth largest theropod dinosaurs known, competing with *Tyrannosaurus*, *Spinosaurus*, *Tyrannotitan* and other massive theropods that lived during the same time-frame. Some scientists put the maximum size at about 43 feet (13 meters long) 8 tons heavy and 12 feet tall at the hips. The relatively incomplete postcranial remains make it difficult to come to a solid conclusion; whereas the mass estimations go about 12 meters.

*Giganotosaurus* has smaller, robust arms, with hooked sickle claws, which could be used to subdue massive prey. *Giganotosaurus* has a pair of strange sagittal crests that start at the fenestra and nasal openings, and grow above the eye orbit, which then abruptly end. The crests overlook the orbits similar to that of an eave. *Giganotosaurus*' muscular jaws are filled with rows of sharp 8 inch long teeth. *Giganotosaurus* has an especially muscular neck, alongside a robust axis at the base of the neck.

## Paleoecology

*Giganotosaurus* lived in Argentina during the Late Cretaceous, and was one of the dominant apex predators in it's ecosystem. Studies on the oxygen isotope patterns in the fossils closely matched the patterns recorded in *Tyrannosaurus*. This tells us that the thermoregulation in dinosaurs was between mammals and reptiles. *Giganotosaurus* would have grown up fast, and, in tern, had a metabolism of about 8 tons. *Giganotosaurus* had an approximate run speed of 14 m/s (50 km/h, 31 mph).

*Giganotosaurus* lived in the Candeleros Formation, deposited about 98 to 94 million years ago. Giganotosaurus lived with the following: sauropods *Andesaurus*, *Limaysaurus*, *Argentinosaurus*, *Nopcsaspondylus*, theropods *Ekrixinatosaurus*, *Buitreraptor* and *Alnashetri*. Miscellaneous reptiles include: the crocodyliform *Araripesuchus*, sphenodontians, snakes and turtles like *Prochelidella*. Other vertebrates include: cladotherian mammals, one genus of pipoid frog, ceratodontiform fishes and several ichnogenera suggest that several ornithopods and pterosaurs also inhabited the region.

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