Another transitional fossil—an intermediate species that shares characteristics with two distinct groups of animals—has been discovered in Argentina: an omnivorous dinosaur.

BUENOS AIRES (AFP) — Scientists have found fossil remains of an omnivorous dinosaur in Argentina — a missing link to the carnivores, a researcher said Monday.

“It is an omnivore — in other words it ate everything (plants and meat) — which is the missing link between carnivorous dinosaurs and giant four-footed herbivores,” said Oscar Alcober, also director of the Natural Sciences Museum in San Juan, 1,200 kilometers (745 miles) west of Buenos Aires.

“This is a very important piece of the puzzle on the origin of dinosaurs,” said Alcober.

Alcober and Ricardo Martinez, chief of the museum’s paleontology division, found the remains three years ago in the Ischigualasto-Valle de la Luna park, north of the provincial capital San Juan. They released their findings Monday in the online journal of peer reviewed science plosone.org.

(The paper doesn’t seem to be posted at the PLoS ONE site yet.)

UPDATE at 2/16/09 3:44:13 pm:

Here’s the paper, if you really want to read it, with the sexy title: A Basal Sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the Early Evolution of Sauropodomorpha.

(Hat tip: Dom.)