April 4, 2022 Scott Kraus

Giganotosaurus Was a Cretaceous Theropod

Giganotosaurus was a theropod dinosaur that lived during the early Cenomanian stage during the mid to late Cretaceous period, about 97 million years ago. A member of the Carnosaur family Carcharodontosauridae, Giganotosaurus belonged to the subfamily Giganotosaurinae. Giganotosaurus is the largest meat-eating dinosaur to have been discovered in South America so far.

Pronounced  GEE-gah-NOTE-oh-SORE-us the name Giganotosaurus comes from the Greek language and means “giant southern lizard”, not “giant lizard” as is often mistakenly thought. This carnivore’s name is also often mispronounced and misspelled as “Gigantosaurus” without the extra letter O.

Quick Facts

About Giganotosaurus

Giganotosaurus was closely related to Carcharodontosaurus from North Africa and Tyrannotitan from South America though it is often compared with the better known Tyrannosaurus Rex.

For many years it was thought that Tyrannosaurus Rex was the largest land-predator to have roamed our earth, that is until the Giganotosaurus was discovered. Palaeontologists think that Giganotosaurus outweighed T.Rex by 1 ton though this doesn’t make Giganotosaurus the largest carnivorous theropod of all time (the largest being Spinosaurus) but it does make it the largest meat-eating dinosaur and theropod of South America and the third largest terrestrial carnivore that is known to date.

What did Giganotosaurus Look Like?

Palaeontologists estimate that Giganotosaurus measured somewhere between 39 to 46 feet in length with original estimates of weighing between 6.5 and 13.3 tons. It is now questioned whether this weight range is accurate however since researchers have indicated that dinosaurs were not as heavy as previously thought.

A dinosaur with a long neck and long head, Giganotosaurus walked upright on two large and powerful back legs and had a long tail. This giant carnivore had two short yet powerful arms with claws on the end of its three-fingered “hands” in addition to strong jaws which meant that it could easily grip and kill prey with its bite-force of more than 1,000 lbs – a force three times less than that of T. Rex.

This dinosaur had the longest skull of any known theropod, measuring between 5.9 and and 6.56 feet in length – to put that into context it means that the Giganotosaurus head on its own was larger than most adult humans, meaning it could have eaten a human in a single bite.

Physical Attributes of Giganotosaurus

This meat-eating dinosaur had 8 inch long sharp arrow-tip shaped teeth which would have been used to slice through the thick hides and skins of its victims. Giganotosaurus would likely have used its hands and feet tipped with three claws to hold down or bring prey items to its mouth. This carnivore’s lower jaws were optimized to inflict wounds via a slicing method. Its mandibula (the part of the jaw that is hinged to open the mouth) was actually reinforced for this purpose.

Considering its huge size and the large skull, Giganotosaurus has an unusually small brain. Based on the shape of it’s skull, palaeontologists think this Theropod’s brain was roughly the same shape as well as size of a banana, making this dinosaur less than intelligent.

It is thought however that Giganotosaurus had a good sense of smell judging from the size of the well-developed olfactory region of the brain that was encased in ossified sphenethmoid (a rigid bone in the skull).

What did Giganotosaurus Eat?

Giganotosaurus was a carnivore. It has been difficult to date to pinpoint any small animals that Giganotosaurus would have preyed upon as there have not being any non-sauropod discoveries in South America for this time period. Palaeontologists have a theory though. Fossils belonging to Titanosaur and Argentinosaur – large herbivores measuring almost 75 feet long were recovered near the remains of Giganotosaurus. This finding leads palaeontologists to speculate that this giant meat-eater preyed on large plant-eating dinosaurs rather than those much smaller than itself.

Some researchers even believe that Giganotosaurus would have hunted in packs similar in style to their relations, the Carcharodontosaurus’. This type of hunting behavior would have made hunting a 50 ton and 98 foot long Argentinosaurus much more feasible.

How did Giganotosaurus Move?

Giganotosaurus was bipedal and would have held its tail erect which provided it with more balance, particularly when running.

Since fossilized track-ways have not been found for Giganotosaurus to date, scientists have to rely on estimating its speeds using morphology. Morphology uses leg length and body mass calculations to determine speed of locomotion. Some believe that due to its size, Giganotosaurus would not have been a particularly fast moving dinosaur.

It has been estimated that Giganotosaurus could run at a maximum speed of 31mph. Any faster than this and it is thought that it’s minimal stability would have been lost. Without stability, Giganotosaurus could have fallen over and be badly injured itself or perhaps even killing itself since it’s short arms not being able to break its fall. Even a non-fatal fall could eventually lead to bone infection from a break or starvation due to an inability to hunt.

Where did Giganotosaurus Live?

Found in what is now Argentina in South America, Giganotosaurus would have lived in the Patagonian desert 97 million years ago on what was then the super continent Gondwana.

Most palaeontologists think that Giganotosaurus would have been too large to have ventured too deep into the swamp forest and would have spent its time feeding out in the open or on the edge of the swamp forest.

The Discovery of Giganotosaurus

In 1993 an amateur fossil hunter, Ruben Dario Carolini, who was a mechanic by profession, discovered an almost complete Giganotosaurus skeleton in Patagonia, South Argentina. This specimen was found at what is now considered the Candeleros Formation. The discovery of this dinosaur was scientifically reported a year later in 1994 after being excavated by palaeontologist Rodolfo Coria.

This Giganotosaurus became the holotype and was approximately 70% complete with parts including the pelvis, back legs, most of the backbone, parts of the skull and the lower jaw. Giganotosaurus was named in 1995 to honor Ruben Carolini and was given the type species name of Giganotosaurus carolinii.

A previous discovery of Giganotosaurus was made earlier in 1987 by Jorge Calvo but this specimen was more fragmentary having only mere fragments of skull remaining. This secondary individuals dentary, the bone of the lower jaw which holds the teeth, from the front part on the left hand side, was 8% bigger than the same bones in the holotype leading palaeontologist to believe that this specimen was larger, perhaps an older adult or male.

The Importance of Giganotosaurus

As more dinosaurs including Giganotosaurus have been discovered it has allowed palaeontologists to gauge and compare sizes of dinosaurs species. The discovery of Giganotosaurus also allowed palaeontologists to deduce more information about the predator prey relationship of dinosaur species in South America during the Cretaceous period.