JORGE GONZÁLEZ AND PABLO LARANo one is sure what, exactly, Tyrannosaurus rex did with its short arms. But Argentinian and American scientists have discovered a new dinosaur species that had the same puzzling feature, they reported this week (July 13) in PLOS One.
Gualicho shinyae, whose 90 million-year-old fossil remains were found in Patagonia, Argentina, was 25 feet long and weighed about a ton—roughly the same size as a polar bear. Yet, full grown, this predator had arms the size of a child’s, New Scientist reported.
G. shinyae and T. rex stem from different evolutionary branches. T. rex’s earliest ancestors had arms that were actually long, study coauthor Peter Makovicky, a paleontologist at the Field Museum of Natural History in Chicago, told The New York Times. But for some reason, T. rex evolved to have stubby arms. Because this trait appears to have arisen independently in G. shinyae and T. rex, they may have served a purpose, according to Makovicky.
Scientists still don’t know what that purpose may ...
