But there were marked differences. Among them, in addition to its distinctive cranial crest, Guanlong was roughly 100 million years older and a fourth the size of its big, bad T. rex cousin. It had three fingers; T. rex had two. Its arms were longer and more delicate, its head smaller and its agility superior to the car-crushing, restroom-ripping monster of "Jurassic Park" movie fame.
While the sex of the two T. rex cousins was impossible to ascertain, Erickson determined their respective ages by examining the growth rings on the inside of their bones. Those of the larger animal had seven closely spaced rings –?revealing rapid growth to young adulthood –?followed by six widely spaced rings corresponding with slower growth to full maturity by the end of its relatively long 13-year life. Its cranial crest would have reached its full size by then, thus providing an accurate model for scientists. The bones of the smaller specimen had only six closely spaced rings and no widely spaced ones, indicating that it was a nearly grown juvenile who died prematurely, not simply a smaller, adult female.
"I study these animals as living organisms, not just as specimens on an evolutionary tree," Erickson said. "For me, it's about how they lived, not just how they died."
Guanlong lived in China –?its remains were found in the Junggar Basin of Xinjiang, in the western reaches of the Gobi Desert. Erickson contends that this discovery is merely the tip of the iceberg in that area. "China has been a hot spot for dinosaur fossils since the 1990s," he said.
Widely publicized research by Erickson –?who also is known as an expert in dinosaur and crocodilian dentition, or bite force –?has helped
Source:Florida State University