Meet T-Rex's Diminutive Ancestor

In the days before Tyrannosaurus Rex roamed the Earth, prehistoric animals lived in fear of its ancestor, the Raptorex. But this petit progenitor of the Tyrannosauri would have been a mere mouthful for the mighty T-Rex.

Paleontologists recently found the remains of the Raptorex in a lake bed in Northern China. Like the Tyrannosaurus Rex, Raptorex sports an over-sized head, itty bitty forearms, strong jaws, and a runner's build — "jaws on legs" as Paul Sereno of the University of Chicago described it — but it was only one hundredth the mass of the T-Rex and stood a mere 3 meters in length.

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It's the combination of its small stature and its classically T-Rex features that has paleontologists excited. Other smaller relatives of the Tyrannosaurus have lacked that dinosaur's tiny forearms and comparatively large head, which has long caused paleontologists to suspect those adaptations were due to the Tyrannosaurus's large size. But finding them on a smaller relation means they will have to rethink the T-Rex's evolutionary development.

Raptorex – a prototype T. rex [New Scientist]

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Raptorex Rendering

Illustration for article titled Meet T-Rexs Diminutive Ancestor

Raptorex Skeleton

Illustration for article titled Meet T-Rexs Diminutive Ancestor
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Illustration for article titled Meet T-Rexs Diminutive Ancestor

T. Rex vs. Raptorex

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Skull Comparison

Illustration for article titled Meet T-Rexs Diminutive Ancestor
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DISCUSSION

A "mere" three meters in length?

I may be metric challenged, but isn't that like a 10-foot critter? Shoot, I wouldn't take on a 10-foot gator, and they can't even sit up. These guys could leap!

I am once again glad that the dinos grew feathers and got tiny.