Canadian researchers have discovered that dinosaurs developed wings earlier than previously believed, and that so-called Ostrich Dinosaurs used their feathers for courting or protecting eggs, not for flight.

Ornithomimosaurs, commonly referred to as Ostrich Dinosaurs, are distant relatives to birds and were believed to be hairless, according to Reuters. Researchers had discovered the fossilized remains of three ornithomimosaurs, one juvenile skeleton and two adult skeletons, in Upper Cretaceous river deposits in Alberta, Canada. The fossils are believed to be around 75 million years old. This is the first evidence of feathered dinosaurs discovered in North America, according to a release from the Royal Tyrell Museum of Paleontology in Alberta.

The research was led by Darla Zelenitsky, from the University of Calgary, along with researchers from the Royal Tyrell Museum and was published in the journal Science. From the fossils, the researchers discovered that ornithomimosaurs were covered in feathers their whole lives.  The juvenile fossils revealed soft downlike feathers that covered the entire body. Ornithomimosaurs did not develop wings until adulthood, according to researchers. By then, the dinosaurs were too big to fly and the wings and feathers were used for reproductive purposes or to protect eggs, according to the BBC.

The Royal Tyrell Museum states, “The discovery, the first to establish the existence of feathers in ornithomimids, suggests that all ostrich-like dinosaurs had feathers.”  More importantly, it proves that dinosaurs evolved wings at a much earlier date than previously believed.

Other feathered dinosaurs have been discovered in Germany and China, but those dinosaurs are from a later period and a more closely related to birds than ornithomimids. “This particular dinosaur is a bit more distantly related to birds - it's a more primitive dinosaur,” Zelenitsky told the BBC.

The discovery is important because the fossils were found in sandstone. According to the Royal Tyrell Museum, dinosaur fossils are commonly found in sandstone around the world, meaning there may be more discoveries of feathered dinosaurs in the near future. By being able to identify the origins of wings and feathers in dinosaurs, researchers can better understand their purpose and their use in different dinosaurs.