Giganotosaurus, the Giant Southern Lizard

giganotosaurus
Giganotosaurus.

Durbed/Wikimedia Commons/CC BY 3.0

An up-and-comer in the elite club of huge, terrifying, meat-eating dinosaurs, in the last few decades Giganotosaurus has attracted almost as much press as Tyrannosaurus rex and Spinosaurus. On the following slides, you'll discover 10 fascinating Giganotosaurus facts—and why, pound for pound, the giant southern lizard may have been even more fearsome than its better-known relatives.

01
of 10

The Name Giganotosaurus Has Nothing to Do With "Gigantic"

giganotosaurus
A Giganotosaurus getting its teeth cleaned.

Sergey Krasovskiy/Wikimedia Commons

Giganotosaurus (pronounced GEE-gah-NO-toe-SORE-us) is Greek for "giant southern lizard," not "gigantic lizard," as it's often mistranslated (and mispronounced by people unfamiliar with classical roots, as "gigantosaurus"). This common error can be attributed to the numerous prehistoric animals that do, in fact, partake of the "giganto" root—two of the most notable examples being the giant feathered dinosaur Gigantoraptor and the giant prehistoric snake Gigantophis

02
of 10

Giganotosaurus Was Bigger than Tyrannosaurus Rex

Animatronic Dinosaurs at Gulliver's

PLTRON/Wikimedia Commons/CC BY 4.0

Part of what has made Giganotosaurus so famous, so quickly, is the fact that it slightly outweighed Tyrannosaurus Rex: full-grown adults may have tipped the scales at about 10 tons, compared to a little over nine tons for a female T. Rex (which outweighed the male of the species). Even still, Giganotosaurus wasn't the biggest meat-eating dinosaur of all time; that honor, pending further fossil discoveries, belongs to the truly humongous ​Spinosaurus of Cretaceous Africa, which had a half-ton or so edge.

03
of 10

Giganotosaurus May Have Preyed on Argentinosaurus

Argentinosaurus

Zachi Evenor/Flickr/CC BY 2.0 

Direct proof is lacking, but the discovery of the bones of the giant titanosaur dinosaur Argentinosaurus in the proximity of those of Giganotosaurus at least hints at an ongoing predator-prey relationship. Since it's hard to imagine even a fully grown Giganotosaurus taking down a 50-ton Argentinosaurus adult, this may be a hint that this late Cretaceous meat-eater hunted in packs, or at least in groups of two or three individuals. (For a blow-by-blow analysis of this encounter, see Giganotosaurus vs. Argentinosaurus.)

04
of 10

Giganotosaurus Was the Largest Meat-Eating Dinosaur of South America

giganotosaurus

 Eva K/Wikimedia Commons

Although it wasn't the largest theropod of the Mesozoic Era—that honor, as stated above, belongs to the African Spinosaurus—Giganotosaurus is secure in its crown as the largest meat-eating dinosaur of Cretaceous South America. (Fittingly enough, its presumed prey Argentinosaurus holds the title of "largest South American titanosaur," though lately there have been numerous pretenders.)  South America, by the way, is where the very first dinosaurs evolved way back during the middle Triassic period, about 230 million years ago (though there is now some evidence that the ultimate ancestor of dinosaurs may have originated in Scotland).

05
of 10

Giganotosaurus Preceded T. Rex by 30 Million Years

tyrannosaurus rex
T. Rex lived millions of years after Giganotosaurus (Wikimedia Commons).

David Monniaux/Wikimedia Commons/CC BY 3.0

Giganotosaurus prowled the plains and woodlands of South America about 95 million years ago, a whopping 30 million years before its more famous relative, Tyrannosaurus Rex, reared its head in North America. Oddly enough, though, Giganotosaurus was a near-contemporary of the biggest known meat-eating dinosaur, Spinosaurus, which lived in Africa. Why were the meat-eating dinosaurs of the late Cretaceous period comparatively petite compared to their middle Cretaceous forebears? No one knows, but it may have had something to do with the prevailing climate or the relative availability of prey.

06
of 10

Giganotosaurus Was Speedier Than T. Rex

Full-size model in Poland, depicting Tyrannosaurus with both feathers and scales, as well as lipped jaws

Marcin Polak/Wikimedia Commons/CC BY 2.0

There has been a lot of debate lately about how fast Tyrannosaurus Rex could run; some experts insist this supposedly fearsome dinosaur could only attain a top speed of a relatively pokey 10 miles per hour. But based on a detailed analysis of its skeletal structure, it seems that Giganotosaurus was a bit fleeter, perhaps capable of sprints of 20 mph or more when chasing down fleet-footed prey, at least for short periods of time. Bear in mind that Giganotosaurus wasn't technically a tyrannosaur, but a type of theropod known as a "carcharodontosaur," and thus related to Carcharodontosaurus.

07
of 10

Giganotosaurus Had an Unusually Small Brain for Its Size

Giganotosaurus skeleton mount at the Fernbank Museum of Natural History in Atlanta, Georgia.

Jonathan Chen/Wikimedia Commons/CC BY 4.0

It may have been bigger and faster than Tyrannosaurus Rex, but oddly enough, Giganotosaurus seems to have been a relative dimwit by middle Cretaceous standards, with a brain only about half the size of its more famous cousin, relative to its body weight (giving this dinosaur a relatively low "encephalization quotient," or EQ). Adding insult to injury, to judge by its long, narrow ​skulll, Giganotosaurus' tiny brain appears to have been the approximate shape and weight of a banana (a fruit that had yet to evolve 100 million years ago).

08
of 10

Giganotosaurus Was Discovered by an Amateur Fossil Hunter

Reconstructed skeleton, EBPM

Neloadino/Wikimedia Commons/CC BY 4.0

Not all dinosaur discoveries can be credited to trained professionals. Giganotosaurus was unearthed in the Patagonian region of Argentina, in 1993, by an amateur fossil hunter named Ruben Dario Carolini, who surely must have been surprised by the size and heft of the skeletal remnants. The paleontologists who examined the "type specimen" acknowledged Carolini's contribution by naming the new dinosaur Giganotosaurus carolinii (to date, this is still the only known Giganotosaurus species).

09
of 10

To Date, No One Has Identified a Complete Giganotosaurus Skeleton

Partial holotype skull (white parts are reconstructed) with left dentary in the background, Ernesto Bachmann Palaeontological Museum

Neloadino/Wikimedia Commons/CC BY 4.0

As is the case with many dinosaurs, Giganotosaurus was  "diagnosed" based on incomplete fossil remains, in this case, a set of bones representing a single adult specimen. The skeleton discovered by Ruben ​Carolini in 1993 is about 70 percent complete, including the skull, hips, and most of the back and leg bones. To date, researchers have identified mere fragments of this dinosaur's skull, belonging to a second individual—which is still enough to peg this dinosaur as a carcharodontosaur.

10
of 10

Giganotosaurus Was Closely Related to Carcharodontosaurus

Carcharodontosaurus

Wikimedia Commons/Public Domain

There's something about giant predatory dinosaurs that inspires paleontologists to come up with cool-sounding names. Carcharodontosaurus ("great white shark lizard") and Tyrannotitan ("giant tyrant") were both close cousins of Giganotosaurus, though the first lived in northern Africa rather than South America. (The exception to this terrifying-name rule is the plain-vanilla-sounding Mapusaurus, aka the "earth lizard," another plus-sized Giganotosaurus relative.)