Updated: December 21, 2012 12:13AM
Dinosaur hunters searching through museums on two continents for fossil bones have discovered what may be the earliest ancestor of all the varied reptiles that roamed the Earth before they became extinct some 65 million years ago.
It probably lived about 245 million years ago, at least 10 million to 15 million years earlier than any other known dinosaurs, the scientists said.
If the creature -- slightly larger than a Labrador retriever, but with a tail more than 5 feet long -- wasn’t the oldest dinosaur of them all, then it was most likely the closest evolutionary relative of any earlier ones, say its discoverers.
Paleontologists Sterling Nesbitt of the University of Washington and Sarah Werning of University of California, Berkeley are leaders of a research team that identified the ancient animal from only one fossilized upper arm bone and six small fossil vertebrae that had been stored for decades in drawers at London’s Natural History Museum. They found more bones at the South African Museum in Cape Town.
But there are no bits of fossilized bone from the dinosaur’s skull, so they could not tell whether the animal was a meat eater or a vegetarian, Werning said.
Werning is a graduate student at Berkeley’s Museum of Paleontology, and her analysis showed that the fossils’ abundant structures of bone and blood vessel cells gave evidence that the animals’ growth rates closely resembled those of early dinosaurs but that they grew faster than their later descendants, she said.
The old bones were first dug up near Lake Nyasa in southwestern Tanzania during the 1930s by an eminent fossil-hunter from Cambridge University named Rex Parrington. Much later, Parrington’s student Alan J. Charig described the fossils in his dissertation in 1975.
Nesbitt, Werning and their colleagues named their dinosaur Nyasasaurus parringtoni, for the lake and Parrington’s name.
Charig, who became a distinguished British paleontologist and a star on BBC science shows, died in 1997 and never formally published his dissertation work. So Nesbitt, Werning and their colleagues listed Charig as a co-author of their report.
“Dr. Charig was like everybody else in this kind of work,” said Werning. “They get intrigued by what they’ve found, and then they get busy and find something else that’s important, and then they just don’t get around to formally publishing the details of what they started.”
Nesbitt, leader of the team, began his work at Berkeley. Intrigued by dinosaurs as a kid, he said, he started working in the lab of UC dinosaur expert Kevin Padian before he enrolled as a UC Berkeley freshman and “majored in dinosaurs” there.
Hans-Dieter Sues, a distinguished paleontologist at the Smithsonian Institution in Washington who was not involved in the new research, said in an email that the report is important because “it indicates the existence of a dinosaur-like reptile many millions of years before the oldest known dinosaurs.”
“Now the existence of such an animal is no longer out of the question,” he said.
The discovery of the early dinosaur in Africa is also significant, experts say, because before now the oldest dinosaurs had been found in Argentina.
This new report adds to the evidence that similar animals must have wandered across the ancient “super-continent” known as Pangaea before it broke up some 200 million years ago and separated Africa from South America, with the Atlantic Ocean forming between.