BUENOS AIRES • Researchers announced yesterday that they have discovered a ferocious meat-eating dinosaur in Argentina, notable for having short arms like the T-rex, but hailing from a different branch of the family tree.

The Gualicho shinyae - nicknamed Gualicho - is a theropod, a two-legged, bird-like dinosaur. It stretched an imposing 6m from head to toe, and weighed an estimated 450kg.

It roughly resembles the Tyrannosaurus rex but Gualicho, found in the north of Argentina's Patagonia region, was not a close relative of the king of dinosaurs. Its stubby limbs evolved independently and not from a shared, short-armed ancestor - a clue that may help researchers better understand how the extinct animals evolved.

"This is a completely different lineage. We just froze up when we realised it," researcher Sebastian Apesteguia at Argentina's National Scientific and Technical Research Council told a briefing in Buenos Aires.

The research on Gualicho in the scientific journal Plos One was led by Dr Apesteguia and expert Ruben Juarez Valieri, a specialist in carnivorous dinosaurs in Argentina's Rio Negro province.

The new dinosaur's name "Gualicho" is in honour of a local indigenous deity with power over animals and the wind.

And "shinyae" is in honour of Ms Akiko Shinya, chief fossil preparator at Chicago's Field Museum, who found the incomplete skeleton while working on the dig.

She said: "We found Gualicho at the very end of the expedition. Pete joked, 'It's the last day, you'd better find something good!' And then I almost immediately was like, 'Pete, I found something.' I could tell right away that it was good."

She was referring to Dr Peter Makovicky, the Field Museum's curator of dinosaurs.

AGENCE FRANCE-PRESSE