New Dinosaur Fossil Uncovered In Argentina Resembles T. Rex

Kirsten Silven - Author
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Jul. 17 2016, Updated 6:21 p.m. ET

A new carnivorous dinosaur fossil discovered in Argentina bears an uncanny resemblance to the puny-armed Tyrannosaurus rex, reported The Guardian. Dubbed Gualicho shinyae, the fossil suggests that the newly discovered dinosaur species lived more than 90 million years ago and was likely a distant relative of T. rex.

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The newly unearthed species of meat-eating dinosaur has long legs, short arms, and two-digit claws, much like the more sizable T. rex, suggesting the animal belonged to a large and very diverse group of two-legged dinosaurs known as theropods. This group also includes both tyrannosaurs and velociraptors. The new dinosaur is believed to have weighed in at around 450 kg (nearly 1,000 pounds) and researchers estimate Gualicho typically measured between six and seven meters in length.

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“What’s odd about him, the thing that sticks out right away, are these really reduced forelimbs, and also the reduction of the digits on the hand as well,” stated Nathan Smith, a co-author of the paper outlining the findings from the Natural History Museum of Los Angeles County. “While early theropods had five primitive digits, the newly unearthed dinosaur does not. He basically had a two-fingered hand.”

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Despite any obvious similarities to T. rex, however, the new dinosaur unearthed in Argentina is only a distant relative. The fact that they share tiny forelimbs shows that the trait evolved independently more than once, since it’s already believed that the T. rex didn’t evolve from a short-armed ancestor, but rather came from a dinosaur with longer arms.

“What we have found is a new… carnivorous dinosaur from… Patagonia from the Cretaceous period,” stated Argentina-based paleontologist Sebastian Apesteguia in an interview with Fox News.

Apesteguia led a team that found and examined the remains of the new dinosaur unearthed in Argentina, and presented the findings Wednesday, when he unveiled a replica of Gualicho. The researchers discovered the bones of the ancient carnivorous dinosaur, making up a partial skeleton of the beast, which weighed more than half a ton and is more than 19 feet long. According to Apesteguia, the newly discovered dinosaur could be related to the African Deltadromaeus dinosaur, which existed during the same epoch and shared a similar bone structure with Gualicho.

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Published in the journal PlosOne by a team of researchers including scientists from the United States and Argentina, the research shows that the new dinosaur joins a variety of other theropods, including the tyrannosaurs and abelisaurs, which also evolved over time to have short, weak – indeed nearly useless – arms.

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“This seems to be a common thing in theropod evolution, a recurring theme.”

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Still, University of Edinburgh researcher Stephen Brusatte said it remains a mystery why the dinosaurs developed such tiny arms. One theory is connected to this particular dinosaur group’s killer bite, thereby reducing the need for highly functional forelimbs. Still, this leaves new unanswered questions, namely why evolution didn’t get rid of the tiny arms entirely if they served no purpose.

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“Smith believes that while there may only be a limited number of ways to evolve reduced forelimbs, the differing anatomy and shape of the limbs and hands between short-armed dinosaurs hints that there could be a range of evolutionary pressures at play.”

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Despite the ongoing mystery surrounding the new dinosaur discovery in Argentina, this latest find is yet one more essential piece of the puzzle that will help solve the many questions that still surround these ancient creatures. The new Gualicho shinyae dinosaur is the newest genus and species of allosaurus to be discovered and its name was derived from two things. First, “Gualicho” is a demon from local folklore and was selected due to the large number of mishaps the research team encountered during the discovery process, while “shinyae” was added as a nod to Akiko Shinya of Chicago’s Field Museum, who first discovered the new dinosaur.

[Image via Shutterstock]

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