Handout picture released by the Museo Paleontologico Trelew showing a real-size replica of the fossil of a Taquetrensis Leonerasaurus dinosaur being exhibited at the museum, in Neuquen, Argentina. Scientists in southern Argentina discovered fossils from this previously unknown species of dinosaur, a herbivore of about three metres long precursor of the great herbivores.

Fossils of a recently discovered dinosaur species in Argentina is a "missing link" in the evolution of the long-necked giants that roamed the earth millions of years ago, paleontologists said.

Long-neck, long-tail plant-eaters like Diplodocus, Brachiosaurus and Brontomerus -- the largest land creatures ever to walk on earth -- are dinosaurs known as sauropods. They lived some 170 million years ago.

Paleontologists see the recently discovered Leonerasaurus Taquetransis as the connection between the smaller prosauropods -- also known as near-sauropods -- like Sellosaurus and Plateosaurus from the Triassic period (248-205 million years ago) to their much larger descendants, the sauropods.

Leonerasaurus lived some 10 million years before the sauropods and measured a mere three meters (yards) long, said Diego Pol with the Egidio Feruglio Museum of Paleontology.

"The importance of this find is that it is a new species. It gives us information on the origin of the sauropods," Pol told AFP.

Leonerasaurus is "a very primitive species... that helps us understand the evolutionary tree of the giants that appeared later," Pol said.

Pol said he made the find along with a geologist and a student in the southern Patagonian mountains of Taquetran at a site with fossil remains from the Jurassic period (206-144 million years ago).

The team however did not find a complete Leonerasaurus. "Parts of the skull and the tail are missing. But the backbone, the hips, front and back legs are there," Pol said.

Argentina earned fame as a prime site for dinosaur fossil hunters starting in the 1980s with several discoveries, including the Argentinosaurus Huinculensis, a giant herbivore measuring more than 40 meters (131 feet) long that lived 98 million years ago.

Later, in 1993, scientists found remains of the Giganotosaurus Carolinii, a T-Rex type creature that is the largest known carnivorous dinosaur ever found.

Pol is the co-author of an article announcing the Leonerasaurus discovery that appeared January in the journal Plos One.

(c) 2011 AFP