Giganotosaurus vs T. rex: Which Was Bigger?

They were about the same length: Giganotosaurus about 12.5 to 13.2 m (41 to 43 ft) (Coria & Salgado 1995; Calvo & Coria 1998), T. rex about 12.3 to 13 m (40 to 43 ft) (Brochu 2003). T. rex was probably the heavier animal, up to about 9.5 tonnes for the largest skeleton (Hutchinson et al. 2011), and it is known from far more complete fossils.

So "which was bigger" depends on the measure, and on how much of each animal has actually been found.

Giganotosaurus vs T. rex at a glance

• Length: Giganotosaurus 12.5 to 13.2 m; T. rex 12.3 to 13 m.
• Weight: Giganotosaurus 6 to 8 t (6.6 to 8.8 short tons) in its original description; T. rex most adults 6 to 8 t, Sue about 9.5 t (10.5 short tons).
• Skull: Giganotosaurus about 1.53 to 1.60 m (5.0 to 5.2 ft) as reconstructed; T. rex shorter but much broader and deeper.
• Hip height (estimated): Giganotosaurus 3 to 3.6 m (very low confidence); T. rex 3.6 to 4 m.
• When: Giganotosaurus about 100 to 94 million years ago; T. rex about 68 to 66 million years ago.
• Where: Giganotosaurus in Patagonia, Argentina; T. rex in western North America.

Which was longer?

Giganotosaurus was described in 1995 by Rodolfo Coria and Leonardo Salgado, who estimated about 12.5 m for the holotype from the Candeleros Formation of Neuquén. A larger referred jaw bone later pushed the estimate to about 13.2 m (Calvo & Coria 1998). T. rex's benchmark, the nearly complete skeleton "Sue", is about 12.3 m, and about 13 m is widely reported for the largest known individual.

The difference is well inside the uncertainty. Scaling a whole animal from a single jaw bone, as with the 13.2 m figure, is exactly the kind of estimate that later work tends to revise.

Which was heavier?

Here T. rex probably wins. Hutchinson and colleagues (2011) modelled five T. rex skeletons and found most adults at 6 to 8 tonnes and Sue at about 9.5. Giganotosaurus was estimated at 6 to 8 tonnes by its describers.

One study went much higher: Therrien and Henderson (2007) estimated about 13.8 tonnes for Giganotosaurus from a skull-length regression, a method that depends on how the incomplete skull is reconstructed. Other published figures start at about 4 tonnes. We keep those as notes on the profile rather than averaging them into a headline.

The builds differ too. T. rex had a deep, wide chest and massive legs; Giganotosaurus was a carcharodontosaurid, with a long, narrower skull and a comparatively slimmer body.

Which had the bigger skull?

Giganotosaurus's skull is usually reconstructed at about 1.53 to 1.60 m, longer than T. rex's. But the Giganotosaurus skull is incomplete, both numbers are reconstructions, and Therrien and Henderson considered them overestimates. The T. rex skull was shorter yet far more robust, built for a bone-crushing bite.

How complete are the skeletons?

This is the biggest difference between the two. T. rex is known from many specimens, including "Sue", one of the most complete large theropod skeletons ever found. Giganotosaurus is known from a partial holotype with an incomplete skull, plus a few referred bones such as the larger jaw. Every Giganotosaurus figure, including its length, is therefore a reconstruction that fills the missing parts from relatives. When the evidence is that uneven, "about the same size" is the honest verdict.

Did Giganotosaurus and T. rex ever meet?

No. Giganotosaurus lived in the Cenomanian, about 100 to 94 million years ago; T. rex at the end of the Maastrichtian, about 68 to 66 million years ago. That is a gap of roughly 26 to 34 million years, on different continents. Giganotosaurus's closest large relative lived in Africa at the same time; see Carcharodontosaurus vs Giganotosaurus.

For every measurement of T. rex and how it is made, read how big was T. rex?

Quick answers

• Was Giganotosaurus bigger than T. rex? About the same length; T. rex was probably heavier.
• How heavy was Giganotosaurus? About 6 to 8 t in its description; one skull-based estimate reached 13.8 t.
• Did they live at the same time? No, some 26 to 34 million years apart, on different continents.
• Which is known from more fossils? T. rex, by far: several good skeletons against one partial Giganotosaurus and a few referred bones.