London, April 28 (IANS): Scientists have stumbled upon a 'weird' relative of the Tyrannosaurus rex. Although closely related to the notoriously carnivorous Tyrannosaurus rex, the new lineage of dinosaur discovered in Chile is weird in the sense that it preferred to graze upon plants.

Paleontologists are referring to Chilesaurus diegosuarezi as a 'platypus' dinosaur because of its extremely bizarre combination of characters that include a proportionally small skull and feet more akin to primitive long-neck dinosaurs.

"Chilesaurus can be considered a 'platypus' dinosaur because different parts of its body resemble those of other dinosaur groups due to mosaic convergent evolution," said researcher Martin Ezcurra from the University of Birmingham.

"In this process, a region or regions of an organism resemble others of unrelated species because of a similar mode of life and evolutionary pressures," Ezcurra explained.

Chilesaurus diegosuarezi is nested within the theropod group of dinosaurs, the dinosaurian group that gathers the famous meat eaters Velociraptor, Carnotaurus and Tyrannosaurus, and from which birds today evolved.

The presence of herbivorous theropods was up until now only known in close relatives of birds, but Chilesaurus shows that a meat-free diet was acquired much earlier than thought.

Till now, more than a dozen Chilesaurus specimens have been excavated, including four complete skeletons -- a first for the Jurassic period in Chile -- and they demonstrate that this dinosaur certainly combined a variety of unique anatomical traits.

Most of the specimens are the size of a turkey, but some isolated bones reveal that the maximum size of Chilesaurus was around three metres long.

Other features present in very different groups of dinosaurs Chilesaurus adopted were robust forelimbs similar to Jurassic theropods such as Allosaurus, although its hands were provided with two blunt fingers, unlike the sharp claws of fellow theropod Velociraptor.

"Chilesaurus was an odd plant-eating dinosaur only to be found in Chile," said lead researcher Fernando Novas from Bernardino Rivadavia Natural Sciences Museum, Argentina.

"However, the recurrent discovery in beds of the Toqui Formation of its bones and skeletons clearly demonstrates that Chilesaurus was, by far, the most abundant dinosaur in southwest Patagonia 145 million years ago," he added.

The findings were published in Nature.