Fossil of new dinosaur class discovered

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Palaeontologists have unearthed the partial remains of a new plant-eating dinosaur which had a body the size of a sheep, a long neck and tail, and lived some 185 million years ago buried in a collapsed sand dune in the western US state of Utah.

The remains were discovered in 2004 by a local artist studying rock paintings and excavated the following year. The nearly complete skeleton is missing only its head, one toe and a lower shinbone.

Scientists said it was rare to find an almost complete skeleton of a new species of dinosaur, and suggestED that the rocks may reveal more extinct animals in the future.

Named Seitaad ruessi, the species is estimated to have been up to 15ft (4.5m) long and about 4ft (1.2m) high. When it was alive, the creature is believed to have weighed between 32-40kg (70-90lbs) and could walk on four legs or stand up and walk on its rear legs.

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Its bones were found protruding from sandstone at the base of a cliff, directly below an ancient Anasazi cliff dwelling in the red rocks of the Navajo Sandstone region.

Researchers believe the animal "was buried in a suddenly collapsing sand dune that engulfed the remains and stood them on their head".

The name Seitaad comes from the word Seit"aad which was a sand monster that buried its victims in dunes in Navajo legend, according to the researchers.

Seitaad ruessi is a sauropodomorph, a type of dinosaur common during the Early Jurassic period, when all of the continents were still joined together in the supercontinent of Pangaea.

It is an ancestor of the giant long-necked, long-tailed dinosaurs such as Diplodocus, Apatosaurus, and Brachiosaurus that roamed Earth in the late Jurassic period.

The study was conducted by palaeontologist Joseph Sertich, a Stony Brook University doctoral student, and Mark Loewen of the Utah Museum of Natural History.

The discovery "confirms the widespread success of sauropodomorph dinosaurs during the Early Jurassic Period," the scientists said.

While dinosaur remains have been found in other parts of Utah, fossils are rare in the Navajo sandstone areas and generally have been from smaller creatures.

This new find suggests that there may be more dinosaurs yet to be discovered in these rocks, said Mr Sertich, co-author of the report and currently a doctoral student at New York"s Stony Brook University.