The single specimen provides a window into what earth was like 120 million years ago. The fossil preserves feathers and bones that provide new information about how did the dinosaurs and how they differed from the birds.

"The new dinosaur fits in with an incredible radiation of animals, feathered and winged are closely related with the origin of birds," said Dr. Ashley Poust, who examined the specimens while he was a student at Montana State University and during his time as a doctor. student of the University of California, Berkeley. Poust is now a postdoctoral researcher at the Natural History Museum of San Diego.

"To study specimens such as this not only shows us the paths sometimes surprising that it has taken the old life, but also allows us to test ideas about what is important that came the characteristics of birds, including the flight, in the distant past."

The scientists named the dinosaur Wulong bohaiensis. Wulong is chinese for "the dragon dancer", and refers to the position of the specimen beautifully articulated.

About the discovery

The specimen was found more than a decade ago by a farmer in China, in the province of Jehol, rich in fossils, and has since been housed in the collection of the Natural History Museum of Dalian in Liaoning, a province of northeast China's border with North Korea and the Sea. The skeletal bones were analyzed by Poust along with his advisor Dr. David Varricchio of Montana State University while Poust was a student there.

Larger than a crow common and smaller than a crow, but with a long tail bone that would have doubled its length, Wulong bohaiensis had a narrow face full of sharp teeth. Its bones were thin and small, and the animal was covered in feathers, including a matrix in the form of ala in his arms and legs and two long feathers at the end of his tail.

This animal is one of the first relatives of Velociraptor, the famous dinosaurio terópodo dromeosáurido that lived approximately 75 million years ago. The closest relative of Wulong would have been a Microraptor, a genus of small dinosaurs paravianos of four wings.

The discovery is significant not only because it describes a dinosaur that is new in science, but also because it shows the connection between birds and dinosaurs.

"The specimen has feathers on its limbs and tail that we associate with adult birds, but had other features that made us think that it was a juvenile," said Poust. To understand this contradiction, the scientists cut several of the bones of the new dinosaur to examine them under a microscope. This technique, called histology, bone, is becoming a regular part of the toolbox of paleontology, but it is sometimes difficult to convince museums to allow a researcher to delete a part of a beautiful skeleton. "Fortunately, our co-authors in the Natural History Museum of Dalian were really forward thinking and allowed us to apply these techniques, not only to Wulong, but also to another dinosaur, a close relative who looked more adult so-called Sinornithosaurus.The bones showed that the new dinosaur was a juvenile. This means that at least some dinosaurs were becoming feathers very mature long before they finish growing. Birds grow very fast and often don't get your feathers adult until well after they are full size. The colorful feathers, especially those used for breeding, are delayed particularly. And yet, here was a dinosaur immature with two long feathers that extended beyond the tip of the tail.

"Or dinosaurs young people needed these tail feathers to some function that we do not know, or were growing their feathers in a very different way to most of the living birds," explained Poust.

A further surprise came from the second dinosaur that the scientists tested; Sinornithosaurus also had not finished growing. The bone tissue was that of an animal in active growth, and lacked a Fundamental System External: a structure on the outside of the bone that the vertebrate form when they are of full size. "Here was an animal that was big and had bones of aspect adult: we thought it was going to be mature, but the histology showed that the idea was wrong. It was more old that Wulong, but it seems to have been growing. Researchers must be very careful when determining whether a specimen is an adult or not. Until we learn more, the histology is really the most reliable way".

Despite these precautions, Poust says there is much more to learn about the dinosaurs.

"We are talking about animals that lived over two times as T. rex, so it's pretty incredible how well preserved they are. It is really very exciting to see the inside of these animals for the first time".