We have found a lost cousin of Tyrannosaurus rex, and it was a far more graceful creature than its more famous relative. Because of its long snout, its discoverers have nicknamed it 鈥淧inocchio rex鈥�.
Big tyrannosaurs like T. rex in North America and Tarbosaurus in Asia are famed for their massive, bone-crunching jaws. These made them apex predators, the terrors of the late Cretaceous world.
Now Junchang L眉 of the in Beijing, China, and his colleagues have described a new species called Qianzhousaurus sinensis. It had an unusually long and narrow jaw that marks it as a different type of predator.
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鈥淭his is a Dobermann pinscher with a long, narrow snout, as opposed to T. rex and Tarbosaurus, which is a pit bull,鈥� says of the University of Maryland in College Park, who was not involved in the research. 鈥淚t鈥檚 another variation on being a tyrannosaur.鈥�
Construction workers found the fossil while excavating in Ganzhou in southern China. It is a nearly complete tyrannosaur, 8 to 9 metres long and with a 90-centimetre-long skull (see picture, below). It weighed about 750 kilograms; lightly built compared to the big guys.
(Image: Junchang L眉)
Qianzhousaurus 鈥渂reaks the mould for what we expect tyrannosaurs to be鈥�, says co-author of the University of Edinburgh, UK. With longer legs and a lighter skeleton than T. rex, 鈥渋t probably was a second-tier predator relying more on speed than on brute strength鈥�. And it probably hunted smaller prey than Tarbosaurus did.
Brusatte previously described called Alioramus from Mongolia, but both were young, and young tyrannosaurs go through a long-snouted stage. The new fossil is nearly full-grown, which means the long-snouted state persisted into adulthood, and so it is the hallmark of a previously unrecognised group.
It is not clear why Qianzhousaurus had such a long face. The long snout would not have been able to resist the high loads and stresses that the skull of T. rex could handle, says of Carthage College in Kenosha, Wisconsin, who was not involved in the research.
Another family of fierce predatory dinosaurs, the spinosaurs, had a snout that was even longer and thinner. But spinosaurs mostly ate fish, so their jaws had enlarged tips with teeth arranged to help trap fish. The jaws of Qianzhousaurus curve smoothly and have buck teeth like T. rex, suggesting its mouth did not evolve to catch fish.
Journal reference: Nature Communications, DOI: 10.1038/ncomms4788
