An ancient bird preserved in amber has been discovered, scientists from China, Canada, and the United States announced in Beijing Friday. It is the most complete fossil ever found.

The amber was found in Hukawng Valley of Kachin State, Myanmar, which is famous for its amber deposits.

The research result has been published on the English-language version of academic periodical Chinese Science Bulletin.

The bird, measuring 5 centimeters in length, was born in the Cretaceous Period, or about 100 million years ago, said Xing Lida, a professor at China University of Geosciences, and also one of the authors of the research paper.

Another co-author, Luis M. Chiappe, director of the Dinosaur Institute at the Natural History Museum of Los Angeles County, said that the bird discovered in the amber is as big as a bee hummingbird, the world’s smallest bird, mainly found in Cuba.

Xing's team had discovered a 7-centimeter bird in amber last June and a tail fossil of a non-avian dinosaur in December 2016.

The new discovery offers more anatomy information such as the base of the skull, spine, left forelimb, pelvis, and thighbone, according to young ornithologist Zou Jingmei, who is also one of the authors.