Giganotosaurus vs. T. rex: Two Dinosaurs With Big Reputations

Tyrannosaurus rex, often shortened to T. rex, is one of the most famous dinosaurs in the world. Its name means "tyrant lizard," and it roamed North America during the late Cretaceous period, roughly 66 million years ago.

Giganotosaurus, meaning "giant southern lizard," lived earlier in the mid-Cretaceous period — about 98 million years ago — in what is now South America. Fossils of both species have given paleontologists a treasure trove of data to study.

When it comes to sheer size, Giganotosaurus edges ahead in length. It may have stretched up to 43 feet (13 meters), while T. rex maxed out closer to 40 feet (12.2 meters).

Then there's the weight comparison. At up to 9 tons (8.2 metric tons), T. rex was among the heaviest theropods — a true tank among predators. Giganotosaurus was even heavier still, maxing out around 14 tons (12.7 metric tonnes).

This is where T. rex has an enormous advantage. Its jaws were bone-crushing machines, capable of delivering up to 12,800 pounds (5,806 kg) of force. That’s enough to shatter bones like twigs.

Giganotosaurus had a long, slender skull built for slicing meat, with sharp teeth better suited for slashing than crunching. In a battle, that powerful bite could give T. rex the upper hand.

Much has been made of T. rex’s tiny arms, but they were strong and may have played a role in grappling prey. Giganotosaurus had slightly longer arms with larger claws, possibly giving it more versatility in an attack.

Still, both relied primarily on their heads and massive bodies to take down prey.

Both dinosaurs were apex predators and likely hunted large prey. These two animals had very different strategies, shaped by their habitats and available prey.

Giganotosaurus may have worked in packs to attack giant titanosaur sauropods. T. rex probably ambushed prey and also scavenged when convenient.

There are far more T. rex specimens than Giganotosaurus fossils, giving scientists more information to work with.

We know more about T. rex’s growth stages, behavior and anatomy, while Giganotosaurus data comes from fewer sources. That said, each discovery adds to the picture.

T. rex has dominated pop culture for decades, from textbooks to toys to Hollywood hits like "Jurassic World Dominion." Giganotosaurus made a memorable appearance in that movie too, introducing many to this lesser-known predator.

This is the ultimate dino showdown. The fight would pit Giganotosaurus's speed and slicing teeth against T. rex’s brute strength and crushing bite. While Giganotosaurus may have been the larger animal, T. rex had the advantage in bite force, mass, and fossil record.

If these two creatures were dropped into a pit, many paleontologists believe T. rex would come out on top.

It helps to think of Giganotosaurus as more like a tiger — fast and agile — while T. rex resembles a massive grizzly bear. Like lions, komodo dragons and other predators, these dinosaurs evolved tools for very specific roles in their ecosystems.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.