Paleontologists uncover game-changing fossil

SALT LAKE CITY — If paleontologists ever achieve a tour de force, they've done so with the discovery a dinosaur-like, mostly plant-eating species almost as old as dirt.

"Not quite that old, but 10 to 15 million years earlier than the oldest known dinosaurs is going back a ways," said Randall Irmis, the unassuming curator of paleontology at the Utah Museum of Natural History and member of the research team that is the buzz on planet science.

The findings overturn the previously held idea that the closest relatives to dinosaurs were two-legged, cat-size predators. The newly designated species, called Asilisaurus kongwe (aSEE-lee-SOAR-us KONG-way), is the first proto-dinosaur recovered from the Triassic Period in Africa, which is roughly 230 million years ago. The species shares many characteristics with dinosaurs but falls just outside the dinosaur family tree. An individual asilisaurus stood about 1 1/2 to 3 feet tall at the hips and was 3 to 10 feet long and weighed between 22 and 66 pounds.

No one was thinking that the closest relatives to dinosaurs would be four-legged herbivores the size of the family dog, Irmis said. The bones were first discovered in 2007, but paleontologists weren't sure what they were looking at until this year.

"It comes as a bit of a surprise," he said, noting the research published in the March 4 issue of the journal Nature also shows that the lineage leading to dinosaurs is both longer and had more ecological diversity than scientists thought.

About 243 million years ago, Irmis said, dinosaurs and the silesaurs — the group that the asilisaurus belongs to — diverged. This discovery came in 2007, when paleontologists working in the Tanzanian grasslands found 14 bone fragments that appeared to come from the dinosaur era but didn't have open hip sockets, an anatomical feature common to all dinosaurs.

The lack of an opening in the hip joint, not unlike the joint in humans, and other data strongly suggested to researchers that dinosaurs and their closest relatives evolved into animals with diets that included plants, Irmis said.

In other words: Adapt or die. Survival of any organism depends on its capacity to adapt and thereby gain an evolutionary advantage in dealing with the one constant of life on earth: change.

"Because the shifts occurred in this relatively short time span, we think the lineage leading to silesaurs and dinosaurs might have had that greater flexibility in adapting, which could well be the reason they managed to succeed for so long," Irmis said.