Gualicho Shinyae is a newly-discovered dinosaur that possessed short, stubby arms similar to those of the more familiar Tyrannosaurus rex. Fossils of this bizarre species were unearthed in Patagonia.
Paleontologists are still puzzled why creatures like the T. rex developed these unusual arms. However, finding similar limbs in other species suggests the design likely served a viable purpose.
Therapoda, one of several suborders of dinosaurs, included both T. rex and G. shinyae. These creatures were noted for their hollow bones and feathers like birds, as well as being bipedal. Therapods exhibited bird-like features throughout their body design. Despite being in the same order, these two species of dinosaurs were members of separate families. Shinyae was an allosaur, unlike its distant relative T. rex. This tells biologists that the short arms of each variety of animal evolved independently from one another.
"Gualicho is kind of a mosaic dinosaur, it has features that you normally see in different kinds of theropods. 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," Peter Makovicky, Curator of Dinosaurs of the Field Museum, said.
This newly-found allosaurid species, roughly the size of a polar bear, weighed in at around 1,000 pounds. Despite the massive size of Gualicho, the arms of the creature were only roughly the size of those seen on a human child.
Investigators found large segments of the body, including parts of the tail, back, hips and front and rear legs. However, the skull remains missing, likely a victim of erosion.
Paleontologists believe its closest relative was the Deltadromeus, an African dinosaur with thin arms.
The name shinyae recognizes the discoverer, Akiko Shinya. The Tehuelche people of Patagonia tell stories of a spirit named Gualichu, providing the inspiration for the genus name. A series of unfortunate events while digging up the fossil, including the overturning of a truck, were experienced by the research team. Investigators joked the experiences were due to a "curse of Gualichu."
Any curse that may have befallen the team in the field, however, was undone on the last day of searching. It was only then that the team found Gualichu.
Gualicho lived around 90 million years before our own time, well before T. rex. That species was not seen until 67 million years ago, roughly two million years before the end of the age of dinosaurs.
Discovery of Gualicho shinyae and analysis of its body shape was detailed in the journal Plos One.