Monday , December 6 2021

Researchers are excited about these "strange" feathers preserved in 100 million years old amber


Feathers in Burmese Amber, dating back 100 million years, are so exquisitely preserved that paleontologists have been able to do a detailed study of their structure – and they are as nothing seen in living birds today.

In fact, they may have served as a type of decoction, which falls into the predator's grip, as a lizard releases its tail to fly.

The feathers, found in 31 Myanmar amber, dating back to the Cretaceous (commonly known as Burmese amber) were analyzed by a team led by Palaeontologist Lida Xing of China's University of Geosciences in Beijing.

You may remember Xing from such Burmese yellow smash hits as 100 million years old bird caught in amber, unlucky frogs caught in amber are the oldest ever found, and of course the absolute epic A spring dance toad stick has been preserved in amber.

These springs are now included in this list of specials. They are called tail currents, and they are tall feathers that extend from the tails of the old birds – sometimes even longer than the birds themselves.

Because modern birds also often have very long tail feathers for ornamental and mating purposes, it was thought that this was why sprout birds also had them.

However, although we have known for Cretaceous bird tail springs for decades, most fossil samples have been restored to be flat, making a more detailed study of their purpose a bit tricky.

The yellow examples – most show that the springs occurred in pairs – are beautifully preserved in all three dimensions. So the team has been able to distinguish its strange morphology and understand a little about how they could have been used by the birds.

"How we interpreted these springs from compression fossils was basically completely wrong. Looking at them in three dimensions preserved in yellow, I was amazed," said Paleontologist Jingmai Connor from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing Science.

"They are the strangest springs I've ever seen."

They are dominated by rachis or the central axis of the spring (the other name they are known of, rachis dominated feathers or RDF). However, as scientists have now noted, the rachis are quite different from the closed cylinder seen in modern birds.

It's rather open on the underside – like a C or U shape – with fewer hooks on both sides than modern springs. Rachis can also be incredibly thin – less than 3 microns in some cases (a human blood cell is an average of 7 microns). But they would still be stuck, straight and tight.

The thinning and shape of the rack causes researchers to think that the springs would have had a lower energy cost to grow – a desirable feature if the springs are available as clues indicate.

For example, some spring patterns that surround RDFs indicate that the spring beat salsa soup with some force, while others were found without signs of a dead bird nearby. According to the researchers, both of these properties suggest that the springs were easy to remove.

They were not as colorful as you would expect from a sexy tail feather.

"The apparent ease of removal and muted colors observed in yellow RDF can indicate a defense role in defense, as well as the usefulness of visual signaling," the researchers wrote in their paper.

"The reduced amount of material involved in building an elongate RDF with an open and thin-walled rachis may have helped reduce the energetic costs of producing springs, as in many cases as long as their wearer's total body length."

But the strange form of rachis seen in these feathers raises more questions, namely, if RDFs were developed from normal feathers, or if they followed another evolutionary path.

This question, however, will require studies of a larger number of RDF ravine samples of exceptionally high quality to respond. Fingers crossed researchers can get their hands on some soon.

The team's research has been published in Journal of Palaeogeography.

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