T. rex look-alike unearthed in Patagonia

 Introducing Paleontology,Animals T. rex look-alike unearthed in Patagonia

Though not a close relative, Gualicho shared those puny arms

By Meghan Rosen 7:00am, August 10, 2016

JUST LIKE REX A newly discovered dinosaur species had a T. rex’s stubby arms, and probably relied on a huge head with a mouthful of teeth for hunting.

©Jorge Gonzalez

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What had two puny arms, lived 90 million years ago and probably chowed down on other dinosaurs? (Hint: It’s not T. rex.)

A new dinosaur discovered in what is now Patagonia had the runty forelimbs of a Tyrannosaurus rex but is no cousin of the giant iconic predator, researchers report July 13 in PLOS ONE.

The new species, Gualicho shinyae, has a close relative in Africa, an analysis of fossils suggests. T. rex’s ancestors, on the other hand, came from Asia.

Gualicho is a “smaller, slimmer, trimmer version of a T. rex,” says study coauthor Peter Makovicky, a paleontologist at the Field Museum in Chicago. It probably weighed about a ton and was longer than a pickup truck.

In 2007, Makovicky’s team discovered Gualicho’s partial skeleton — including those impractical arms. The dinosaur probably caught prey with its huge head, Makovicky says. Though the researchers haven’t dug up a skull yet, tiny arms seem to be a trade-off for a big head. Finding Gualicho’s skull would help nail down that idea, he adds.

Gualicho may have fed on grazers called ornithopods, such as duck-billed dinosaurs. Or perhaps it fed on the long-necked, long-tailed sauropods, which were common in the region. But only the youngsters. Sauropod adults were gigantic, Makovicky says, definitely not prey for a (relatively) little guy like Gualicho.

Citations

S. Apesteguía et al. An unusual new theropod with a didactyl manus from the Upper Cretaceous of Patagonia, Argentina. Published online July 13, 2016. doi:10.1371/journal.pone/0157793.

Further Reading

M. Rosen. How to tell if a T. rex is expecting. Science News. Vol. 189, April 16, p. 16.

B. Geiger. New tyrannosaur bridges gap from medium to monstrous. Science News Online, March 14, 2016.

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T. rex look-alike unearthed in Patagonia