A research team including Hokkaido University scientists has discovered the skeleton of a new dinosaur in Mongolia that was curled up in a position like that of a sleeping modern-day bird.
The team's study was published online in the U.S. journal PLOS One on Thursday.
In August 2016, the team, including Hokkaido University professor Yoshitsugu Kobayashi, unearthed the nearly complete fossil skeleton of the dinosaur, named Jaculinykus yaruui, which means "speedy dragon claw."
The focal point of the discovery is that evidence of the dinosaur's behavior was preserved, something rarely seen in fossils, Kobayashi said, noting the importance of the finding for research into how dinosaurs evolved into birds.
Believed to be from around 70 million years ago during the Late Cretaceous period, the new alvarezsaurid dinosaur specimen was discovered in the Nemegt area in the southwestern part of the Gobi Desert in a joint excavation project with a Mongolian institute.
While alvarezsaurid dinosaurs had birdlike features, the team found that the Jaculinykus yaruui is a new species because of its unique features, such as a large protrusion near its tibia.
According to the team, the specimen was found with its head tucked into its body and its legs folded, much like how birds sleep. The team believes that the posture was associated with heat conservation.
The team said that, through the discovery of the fossil remains, it has been able to trace the history of avian sleeping behavior further.