The remains of a prehistoric baby bird have been found preserved in a 99-million-year-old piece of amber in Myanmar. 

It's one of the most detailed specimens ever discovered — complete with scales, feathers and claws — in a region known for its deposits from the Cretaceous period, which lasted from 145.5 to 65.5 million years ago.

'We've had more complete specimens ... but never with this level of detail.' - Ryan McKellar, Royal Saskatchewan Museum

"We've had more complete specimens, where you get more of the skeleton preserved, from compression fossils, but never with this level of detail," Ryan McKellar, curator of invertebrate paleontology at the Royal Saskatchewan Museum, told CBC News.

It even has other remnants of prehistoric life, like insects and mites, trapped inside.

"It's like a little diorama," said McKellar.

Amber bird specimen

The complete specimen of Belone, the 99-million-year-old hatchling found trapped in amber in Myanmar. (Lida Xing)

The miner who collected the specimen at a commercial amber mine in 2014 thought it was a lizard claw, but the director of the Hupoge Amber Museum was sure it was the foot of a small bird. 

That's how the specimen — nicknamed "Belone" (a local term for an amber-coloured bird called the Oriental skylark) — ended up with paleontologist Lida Xing, of the China University of Geosciences.

Using a CT scan, Xing and his team found hidden structures within that revealed the skull and even vertebrae. Using that imagery, and without destroying the sample, they were able to create a complete 3D model of all the bird, which they published in a paper in Gondwana Research.

Amber bird hatchling

A 3D reconstruction of the bird in the position in which it was preserved in a chunk of amber. (Chung Tat)

'Evolutionary holdover'

Belone belongs to a group of birds called the Enantiornithes, which differ from their modern-day peers in many ways. This was an extraordinary bird, McKellar said.

"They're coming out of the egg with feathers on and the ability to fly within the first day or two, with claws that help them clamber up the sides of trees pretty quickly," McKellar said.

Amber bird specimen

A close-up of the wing, which contains incredible detail never before seen in an amber bird specimen. (Ming Bai)

Belone is believed to have been preserved in the amber when it was just days or weeks old.

As for its feathers, the bird had different kinds: some that paleontologists have seen on dinosaurs, but others that are closer to modern-day birds. This, McKellar said, was one of the most surprising and rewarding finds. 

Belone lived during a period when triceratops roamed the land along with velociraptors and the Albertosaurus. Enantiornithes was a group of birds that was among the most abundant and diverse known from the Mesozoic era. However, they went extinct at the end of the Cretaceous period.

"We have a sort of evolutionary holdover from this particular specimen," he said.

McKellar, along with Xing, were also lead researchers of a find announced last December of a dinosaur feather trapped in amber from the same location.

The area has been mined for amber for the past 2,000 years and is one of the richest sites of its kind, which is why there have been quite a few discoveries of late. However, not all prehistoric finds make their way into museums. He hopes that will change as people recognize the significance of such discoveries can make to better understanding Earth's prehistoric past.

"The more of these samples we get, the better or more complete picture we get," said McKellar.