The Tyrannosaurus rex's family tree reaches back at least 100 million years before it roamed the Earth, according to the Oliver Rauhut, a paleontologist at Munich's Ludwig-Maximilian University.

Based on a nearly forgotten fossil of a dinosaur's skull at London's Natural History Museum, he and his team of researchers with the help of Dr. Angela Milner, also from the Natural History Museum, found that a smaller dinosaur, called the Proceratosaurus, weighed just 40 kilograms (88 pounds) and resembled the up to eight-ton T. rex in a number of ways.

"We can say conclusively it's the earliest representative of the line of evolution that led to Tyrannosaurus," Milner said.

Similar to Tyrannosaurus

The Proceratosaurus shows that some of the key features of the Tyrannosaurus rex evolved over millions of years, Rauhut said.

"While hunting, it relied primarily on its powerful bite like the tyrannosauridae would later," he said on Wednesday. "Proceratosaurus also confirms that the tyrannosauridae developed over a very long stretch of time, and gave rise to a great diversity of forms. Further members of the family surely await discovery."

The scientists performed a series of CT and other imaging techniques on the 28-centimeter (11-inch) skull

"Computerized tomography is a wonderful method, because it offers us a non-destructive means of visualizing the internal structures of fossils," Milner said.

Rediscovering history

Proceratosaurus also walked on two feet, had short arms, a powerful tail and extremely sharp teeth, Rauhut added. The group of huge carnivores called tyrannosaurs roamed the land about 85 million to 65 million years ago.

Uncovered in western England nearly a century ago, Rauhut said he was surprised the skull languished in the museum for so long escaping scientists' interest.

"It is quite astonishing that this fossil has received so little attention," he said. "It is one of the best preserved dinosaur skulls in Europe."

sms/dpa/AP
Editor: Mark Mattox