Scientists find early dinosaur cousin

Published Mar 4, 2010

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Paris - Scientists have uncovered the bones of a dinosaur-like creature that roamed Earth at least 10 million years earlier than the oldest known dinosaur, according to a study published on Thursday.

Discovered in Tanzania, Asilisaurus kongwe would have been waist high to a human. It ate plants and lived 240 million years ago.

Researchers for the study, which was published in Nature, said the discovery meant that dinosaurs had probably appeared much earlier than previously thought.

They said it also pointed to a rich variety of fauna during the crucial period before dinosaurs began their 165 million year domination of the planet.

"This new evidence suggests they were really only one of several large and distinct groups of animals that exploded in diversity in the Triassic, including silesaurs, pterosaurs, and several groups of crocodilian relatives," said Sterling Nesbitt, a researcher at the University of Texas in Austin.

Pterosaurs were flying reptiles.

The newly found creature is a silesaur, which Nesbitt described as a "sister" taxon to the one that gave rise to dinosaurs.

Their evolutionary relationship would be roughly analogous to that between humans and chimps, whose genomes overlap by 99 percent, he said.

Silesaurs and dinosaurs lived side by side throughout much of the Triassic Period, between 250 million and 200 million years ago.

Fossil bones from at least 14 Asilisaurus specimens were recovered from a site in southern Tanzania. Scientists were able to reconstruct a nearly complete skeleton, with only small portions of the head and hand missing.

The animals stood 0.5m to 1m tall, and were 1m to 3m long. They weighed between 10kg and 30kg, and walked on all four legs.

The shape of the teeth and a beak-like lower jaw suggest that they could eat meat or plants.

Scientists speculated that the animals were originally carnivores but evolved into omnivores to enhance their chances of survival.

Although they did not persist as long as dinosaurs, silesaurs had a good run, lasting 45 million years.

The first specimen from the silesaur group was discovered only in 2003, but since then eight other specimens have been dug up from Triassic rock around the globe.

"This goes to show that there are whole groups of animals out there that we've never even found evidence of that were very abundant during the Triassic," Nesbitt said.

The names Asilisaurus kongwe comes from "asili", which means "founder" in Swahili, "sauros", the Greek for "lizard", and "kongwe", Swahili for "ancient". - Sapa-AFP

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