“Granddaddy of T. Rex” identified
and World Science staff
Fossil hunters in China say they have uncovered the most primitive member of the dinosaur group that went on to include the fearsome Tyrannosaurus rex.
The creature, about three meters (almost 10 feet) long, was found in the Junggar basin in the northwest of the country. It represents perhaps the earliest tyrannosaur, researchers said, allowing palaeontologists a glimpse of one of the murkiest chapters of dinosaur evolution.
The dinosaur hails from the Late Jurassic period, around 160 million years ago, the said. T. rex lived much later, during the Late Cretaceous period that followed the Jurassic, despite starring in the Hollywood blockbuster “Jurassic Park.”
Nevertheless, the new species shares several limb characteristics with later dinosaurs, suggesting that it too was a fierce predator, say Xing Xu and colleagues of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.
They described the fossil in this week’s issue of the research journal Nature.
The dinosaur’s skull also features a huge nasal crest—a surprise in such a primitive animal, the researchers report. They speculate that this structure may even have been a cumbersome sexual ornament, similar to the peacock’s tail or the elk’s antlers.
The crest is “the most elaborate known in any non-avian dinosaur,” wrote Xu and colleagues in the paper. Since most biologists now believe birds are modern dinosaurs, scientists use the term non-avian dinosaur for the reptilian creatures we normally think of as dinosaurs.
“Details of the anatomy of this relatively small species indicate that it is the most ancient known member of the line that led to Tyrannosaurus rex and its giant kin, the Tyrannosauridae or ‘tyrant dinosaurs,’” wrote Thomas R. Holtz of the University of Maryland in College Park, Md., in a commentary in the same issue of the journal.
“The most spectacular feature of Guanlong is its crest. All tyrannosauroids have some ornamentation along their nasal bones.... But this newly discovered form has an especially impressive example—a tall, narrow projection with numerous hollow excavations,” Holt wrote.
“The fragile nature of these structures suggests that they served for visual signalling, and so for species recognition and mating displays, rather than as weapons.”
The finding supports a relatively new theory that tyrannosaurids arose from swift, smaller-bodied dinosaurs of the Jurassic called coelurosaurs, he added. Older theories held that they arose from a group of bigger ancestors with huge claws, called caurnosaurians.
But the finding, Holt noted, is merely the latest in a trail of ever-more primitive members of the T. Rex ancestral family. So an even older one could turn up. “The new ‘crowned dragon’ of Xinjiang is simply the latest discovery on the trail leading back to the origin of the tyrant kings,” he wrote.
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