Researchers discover dinosaur tail perfectly preserved in amber

Researchers have discovered the tail of a 99-million-year-old dinosaur complete with its feathers and perfectly preserved in a piece of amber from Myanmar.

The finding helps to fill in details of the dinosaurs' feather structure and evolution, which can not be determined from fossil evidence, the researchers said.

While the feathers are not the first to be found in amber, earlier specimens have been difficult to definitively link to their source animal, they said.

"The new material preserves a tail consisting of eight vertebrae from a juvenile; these are surrounded by feathers that are preserved in 3D and with microscopic detail," said Ryan McKellar of the Royal Saskatchewan Museum in Canada.

This photograph shows the tip of a preserved dinosaur tail section, showing carbon film at its surface exposure, and feathers arranged in keels down both sides of tail.

"We can be sure of the source because the vertebrae are not fused into a rod or pygostyle as in modern birds and their closest relatives. Instead, the tail is long and flexible, with keels of feathers running down each side," said McKellar.

In other words, the feathers definitely are those of a dinosaur not a prehistoric bird.

The study's first author Lida Xing from the China University of Geosciences in Beijing discovered the remarkable specimen at an amber market in Myitkyina, Myanmar in 2015.

.@royalsaskmuseum "I have been thinking...This may be the coolest find in my life." Lida Xing pic.twitter.com/xt5ccD1VDx

— Mostly Mammoths (@MostlyMammoths) December 8, 2016

The amber piece was originally seen as some kind of plant inclusion and destined to become a curiosity or piece of jewelry, but Xing recognised its potential scientific importance and suggested that the Dexu Institute of Palaeontology buy the specimen.

The researchers said that the specimen represents the feathered tail of a non-avialan theropod preserved in mid-Cretaceous amber about 99 million years ago.

While it was initially difficult to make out the details of the amber inclusion, Xing and his colleagues relied on CT scanning and microscopic observations to get a closer look.

The feathers suggest that the tail had a chestnut-brown upper surface and a pale or white underside. The specimen also offers insight into feather evolution. The feathers lack a well-developed central shaft or rachis.

Their structure suggests that the two finest tiers of branching in modern feathers, known as barbs and barbules, arose before a rachis formed.

The researchers also examined the chemistry of the tail inclusion where it was exposed at the surface of the amber.

The analysis shows that the soft tissue layer around the bones retained traces of ferrous iron, a relic left over from hemoglobin that was also trapped in the sample.

The findings show the value of amber as a supplement to the fossil record, researchers said.

We are honoured to be a part of the study of a unique and rare find: A feathered dinosaur tail trapped in amber. https://t.co/8DYjj5MhXk pic.twitter.com/gHmmSQAEPG

— Royal Sask Museum (@royalsaskmuseum) December 8, 2016

"Amber pieces preserve tiny snapshots of ancient ecosystems, but they record microscopic details, three-dimensional arrangements, and labile tissues that are difficult to study in other settings," McKellar said.

The finding was published in the journal Current Biology.