This discovery is a pretty significant find. It supports a model for the evolution of feathers that has previously relied on compression fossils that are difficult to interpret and have been hotly debated.

Also, the amber-entombed feathers show that some of the most primitive feather types, also known as protofeathers, were still around just before the dinosaurs went extinct. They existed alongside feathers that are nearly identical to those of modern birds. Given what we know about the animals that were alive in the area at the time, it is reasonable to suggest that the protofeather-like specimens are attributable to dinosaurs and are the first specimens of this type of feather to be recovered from amber.

How does amber preservation work exactly?

Preservation in amber can vary quite a bit among deposits. Amber tends to preserve specimens in great detail because tree resin has antibacterial and drying properties that partially mummify inclusions and slow the initial onslaught of decay. Over many years, the resin polymerizes, turning into a plastic-like substance that is quite resilient, but burial usually results in heating that can have a profound effect on the inclusions over the span of millions of years.

The Canadian amber insect inclusions are largely preserved as hollow voids in the amber, with a thin film of carbonized, coal-like material, where the outside of the insect once was. The feathers appear to have fared much better, because they are fine and are not composed of material that decay easily. That said, many of the specimens show signs of partial decay, and there is no indication of how much, if any, original material remains intact.

What's the backstory of these specimens?

What originally got me interested in this project was a single feather fragment trapped in a spider web that had been given to Dr. Brian Chatterton. For my Ph.D. project, I worked on tiny, less than three millimeter, parasitic wasps trapped within amber from the same deposit. As part of this project I was able to go through the Royal Tyrrell Museum of Palaeontology collection of 3,000 or so inclusions in great detail. After finding a lot of feather fragments in this collection, I had the good fortune of meeting the Leuck family, amateur collectors in southern Alberta, who donated a pair of additional specimens to the University of Alberta. Later, we learned that Dr. Philip Currie was also examining a trio of specimens from the deposit. We pooled the material, creating a surprisingly rich snapshot of feathers in the Late Cretaceous.

This project underlines the importance of maintaining museum collections as well as the role that interested amateurs can play in palaeontology. Without these, there is no way that we would have been able to observe these important specimens.

According to your paper, these feathers represent several distinct stages of feather evolution. Could you explain each stage briefly?