06-29-2006, 04:35 AM
Tyrannosaurus Rex Ancestor Found In China
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Scientists exploring the remote badlands of northwestern China have unearthed the earliest known ancestor of Tyrannosaurus rex, the fierce predatory dinosaur whose image has haunted legends, films and the nightmares of children for more than a century.
The primitive ancestor that lived 160 million years ago was a mere 10 feet long when it was alive, compared to the monster T. rex, who measured more than 40 feet from head to tail and dominated all the dinosaurs on Earth more than 90 million years later. Unlike T. rex, the smaller creature bore a striking but fragile crest atop its head, three fingers on the hands of its surprisingly long forearms and a long, slender snout.
To scientists, the find provides new clues to the evolution of the meat-eating dinosaur tribes known as therapods whose ancestral lineage relates them all to the world's birds of today.
The crested dinosaur has been named Guanlong wucaii, meaning "crowned dragon of the five-colored rocks" -- a reference both to the crest that runs from its nose to the back of its head and the colorful layers of sediment where two of the beasts, one atop the other, were discovered three years ago.
Scenes in the hit Chinese movie "Crouching Tiger, Hidden Dragon" were filmed in the same rocky region, not far from the borders of the Gobi Desert. But back when Guanlong wucaii walked the Earth, rivers, lakes and swamps filled the landscape.
James Clark, a paleontologist at George Washington University, and Xing Xu of China's Institute of Paleontology and Paleoanthropology discovered the skeletons in a layer of rock in China's oil-rich autonomous region of Xinjiang. They are the principal authors of a report on the find appearing today in the journal Nature.
Bones of the skeletons indicate that one was a fully mature adult, about 12 years old when it died, while the other was a juvenile, only 6 years old. Both apparently sank to their deaths in a swamp. The skeleton of the juvenile was found lying above the older one, with a bare inch of sediment separating them, Clark said Wednesday at a Washington news conference.
The large crest atop the dinosaur's head, Clark said, is a major mystery because its function is unclear. It is more than 2 inches high and extremely thin -- no thicker than a tortilla, he said, and appears to be filled with air sacs. "It was probably a display structure, but its meaning is open for debate," Clark said.
The crest, he said, is somewhat similar to the crests on several species of modern birds, like cassowaries and hornbills.
Only two years ago, Xu and Mark Norell of the American Museum of Natural History in New York found a much smaller feathered dinosaur in China that was also an early ancestor of T. rex. Named Dilong paradoxus, it lived about 130 million years ago, bore a ridge rather than a crest atop its head, and now appears to be part of the evolutionary line that includes all the ancient tyrannosaur reptiles.
Kevin Padian, an expert on dinosaur evolution at UC Berkeley, said the newest find is particularly interesting because in some respects, Guanlong seems intermediate between Dilong and T. rex. Guanlong differs from later members of tyrannosaurus family in that it had three fingers, while future tribe members had only two. No other tyrannosaurus had a crest.
"But that's how evolution works sometimes: intermediate in many respects, unique in others," Padian said.
Thomas Holtz Jr. of the University of Maryland, another specialist in dinosaur evolution, suggested in a Nature commentary on the discovery that crests like Guanlong's may have served for visual signaling, species recognition or perhaps for mating displays -- although the scientists who analyzed the Guanlong skeletons could not determine their sex.
"The new 'crowned dragon' of Xinjiang is simply the latest discovery on the trail leading back to the origin of the tyrant kings," Holtz wrote.
E-mail David Perlman at [email protected].
Page A - 5
Source:
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2006/02/09/MNGH6H58GM1.DTL&feed=rss.news (29 June 2006)
Scientists exploring the remote badlands of northwestern China have unearthed the earliest known ancestor of Tyrannosaurus rex, the fierce predatory dinosaur whose image has haunted legends, films and the nightmares of children for more than a century.
The primitive ancestor that lived 160 million years ago was a mere 10 feet long when it was alive, compared to the monster T. rex, who measured more than 40 feet from head to tail and dominated all the dinosaurs on Earth more than 90 million years later. Unlike T. rex, the smaller creature bore a striking but fragile crest atop its head, three fingers on the hands of its surprisingly long forearms and a long, slender snout.
To scientists, the find provides new clues to the evolution of the meat-eating dinosaur tribes known as therapods whose ancestral lineage relates them all to the world's birds of today.
The crested dinosaur has been named Guanlong wucaii, meaning "crowned dragon of the five-colored rocks" -- a reference both to the crest that runs from its nose to the back of its head and the colorful layers of sediment where two of the beasts, one atop the other, were discovered three years ago.
Scenes in the hit Chinese movie "Crouching Tiger, Hidden Dragon" were filmed in the same rocky region, not far from the borders of the Gobi Desert. But back when Guanlong wucaii walked the Earth, rivers, lakes and swamps filled the landscape.
James Clark, a paleontologist at George Washington University, and Xing Xu of China's Institute of Paleontology and Paleoanthropology discovered the skeletons in a layer of rock in China's oil-rich autonomous region of Xinjiang. They are the principal authors of a report on the find appearing today in the journal Nature.
Bones of the skeletons indicate that one was a fully mature adult, about 12 years old when it died, while the other was a juvenile, only 6 years old. Both apparently sank to their deaths in a swamp. The skeleton of the juvenile was found lying above the older one, with a bare inch of sediment separating them, Clark said Wednesday at a Washington news conference.
The large crest atop the dinosaur's head, Clark said, is a major mystery because its function is unclear. It is more than 2 inches high and extremely thin -- no thicker than a tortilla, he said, and appears to be filled with air sacs. "It was probably a display structure, but its meaning is open for debate," Clark said.
The crest, he said, is somewhat similar to the crests on several species of modern birds, like cassowaries and hornbills.
Only two years ago, Xu and Mark Norell of the American Museum of Natural History in New York found a much smaller feathered dinosaur in China that was also an early ancestor of T. rex. Named Dilong paradoxus, it lived about 130 million years ago, bore a ridge rather than a crest atop its head, and now appears to be part of the evolutionary line that includes all the ancient tyrannosaur reptiles.
Kevin Padian, an expert on dinosaur evolution at UC Berkeley, said the newest find is particularly interesting because in some respects, Guanlong seems intermediate between Dilong and T. rex. Guanlong differs from later members of tyrannosaurus family in that it had three fingers, while future tribe members had only two. No other tyrannosaurus had a crest.
"But that's how evolution works sometimes: intermediate in many respects, unique in others," Padian said.
Thomas Holtz Jr. of the University of Maryland, another specialist in dinosaur evolution, suggested in a Nature commentary on the discovery that crests like Guanlong's may have served for visual signaling, species recognition or perhaps for mating displays -- although the scientists who analyzed the Guanlong skeletons could not determine their sex.
"The new 'crowned dragon' of Xinjiang is simply the latest discovery on the trail leading back to the origin of the tyrant kings," Holtz wrote.
E-mail David Perlman at [email protected].
Page A - 5
Source:
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2006/02/09/MNGH6H58GM1.DTL&feed=rss.news (29 June 2006)
