Millions of years before the first tremendous Tyrannosaurus rex began terrorizing fellow animals, Raptorex kriegsteini showed all of the characteristic tyrannosaur features—in miniature.

Weighing in at about 1 percent of the latter theropod's mass, Raptorex hunted with the same bipedal gait, stubby arms and keen sense of smell as its daunting cousin. Despite being a fairly diminutive dino, it still was nearly three meters long, weighed about 80 kilograms and would have been a fearsome match for a midsize mammal like a human.

"There's no other example that I can think of where an animal has been so finely designed at about 100th the size that it would eventually become," Paul Sereno, a paleontologist at the University of Chicago, said in a prepared statement. He and five other co-authors describe the new carnivore in a paper in Science today.

In this image, the Raptorex's skull is shown to be just a fraction the size of a full-grown T. rex skull.