Scientists have discovered a new species of meat-eating dinosaur in Argentina, which has small, short arms like those seen on the Tyrannosaurus Rex.
The new creature has been named Gualicho Shinyae, and its arms sparked hopes that a new relative of the T.Rex had been discovered. However scientists have since revealed that the new creature is not related to the most iconic dinosaur, and its arms evolved independently, according to the BBC.
Discovery of dinosaur during Patagonia trip
Gualicho Shinyae was found in northern Patagonia, and the 90 million year old animal measured approximately 7.6m in length, weighing around a ton. Full details of the work carried out by an international group of scientists was published in the journal Plos One.
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The new discovery is a theropod, just like T.Rex. This means it is a two-legged, bird-like dinosaur. However the two are from different parts of the family tree.
“Gualicho is kind of a mosaic dinosaur, it has features that you normally see in different kinds of theropods,” said co-author Peter Makovicky, from The Field Museum in Chicago, US.
Scientists intrigued by Gualicho Shinyae
Gualicho is found on a part of the family tree that suggests it got its small forelimbs due to a separate process than those of other carnivorous dinosaurs. It is unlikely that the shared characteristic arose due to a shared ancestor.
“It’s really unusual—it’s different from the other carnivorous dinosaurs found in the same rock formation, and it doesn’t fit neatly into any category,” said Dr Makovicky.
The dinosaur, which was relatively large, had forelimbs the same size as those of a human child. It is a common theme among therapods, although scientists do not know why.
One explanation is the fact that the dinosaur had incredibly strong jaws. “A pretty straightforward explanation, you would think, is that the limbs are being reduced in these lineages that probably are relying more on the jaws for prey capture,” said Nathan Smith, a co-author of the paper from the Natural History Museum of Los Angeles County.
However that does not seem like a complete answer. “The arms had less and less to do, so they got smaller. But they must have still been doing something, or else evolution would probably have just gotten rid of them entirely,” said Stephen Brusatte of the University of Edinburgh.
Unlucky research trip ends with fascinating find
Gualicho Shinyae also had only thumb and forefinger, the same as the T.Rex.
“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,” said Smith. Early theropods had five primitive digits, but the newly discovered dinosaur does not. “He had basically a two-fingered hand,” said Smith.
Gualicho Shinyae is a new genus of dinosaur and a new species of allosaur. Its name is a reference to Akiko Shinya of the Field Museum in Chicago, who made the discovery, and a demon of local folklore known as Gualichu. According to researchers the latter was picked to reflect the bad luck which plagued the team.
Scientists were coming towards the end of a research expedition in Patagonia when they made the find. “About halfway through the trip I flipped a truck,” said Peter Makovicky, a co-author of the paper from the Field Museum. “Thankfully, everyone walked away from that” he added.