There's only so much palaeontologists can learn about prehistoric animals from fossilized bones, so on rare occasions when ancient soft tissues turn up, it's worth taking note. Recent discoveries of preserved brains, cartilage and skin have provided some unique insights into how dinosaurs may have looked and sounded, and now a section of a dinosaur's tail, complete with feathers, has been found trapped in a piece of amber.

The study's first author, Lida Xing, uncovered the relic, but not at a dig site – it turned up at an amber market in Myanmar in 2015. Originally thought to contain some kind of plant, Xing saved the important find from becoming a tacky piece of jewellery, and the Dexu Institute of Palaeontology snapped it up for study.

Feathers have turned up in amber before, but this discovery is the first to be found connected to bone and other tissue, allowing the scientists to narrow the owner's species down to a dinosaur from the Coelurosaur family, a subgroup of therapods that includes modern-day birds as well as the mighty Tyrannosaurus Rex.

"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," says Ryan McKellar, of the Royal Saskatchewan Museum in Canada. "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."

The specimen hails from the mid-Cretaceous period around 99 million years ago, and judging by the color of the feathers, the animal (or at least its tail) would've been chestnut-brown on top, with a pale underside. Compared to those of modern animals, the feathers themselves are oddly-shaped with no well-defined shaft down the middle, hinting that in evolutionary terms, the finer branches at the tips of feathers, known as barbs and barbules, developed earlier than the central shaft.

CT scans and microscopic observations helped the researchers peer through the murky amber, and by performing a chemical analysis of the soft tissue where the tail meets the surface of the material, the scientists found traces of ferrous iron, a compound from the animal's red blood cells. These kinds of discoveries can't be found in the fossil record alone.

"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," says McKellar. "This is a new source of information that is worth researching with intensity and protecting as a fossil resource."

The scientists are on the hunt for other potential finds in the region, in the hopes of furthering the study of dinosaur plumage and tissue.

The research was published in the journal Current Biology.

Source: Cell Press via Eurekalert

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