Fossilised Feathers Preserved in Cretaceous Amber Provide Insight into Ancient Ecosystem

An analysis of many thousands of amber nodules from Alberta in Canada has led to the discovery of a number of prehistoric feathers that had become entombed.  Scientists have been able to study the perfectly preserved filaments and this has given them more information on the diversity of feathered creatures that lived in Alberta during the Late Cretaceous.  Although it is not possible to distinguish dinosaur feathers from the feathers found on birds, the different feather types found indicate that there were a wide variety of feathered creatures in the swampland and tropical lowland jungle that was Alberta towards the end of the reign of the dinosaurs.

Amber is a sticky, scented resin produced by certain types of trees as protection against damage to their bark.  Insects, plant debris and now even feathers become stuck in the resin and when it fossilises it becomes amber, preserving fragments of a prehistoric world within it.

Fossilised Feathers

Over the last few years there have been some remarkable discoveries made by studying the contents of amber nodules.  The resin covers and entombs organic matter permitting some extremely rare and fragile fossils to be formed, that would not survive other fossilisation processes.  For example, a few years ago scientists discovered preserved spider silk in an amber nodule.

To read more about this amazing discovery: World’s Oldest Spider’s Web Found Preserved in Amber.

The research from a University of Alberta team and published this week in the scientific journal “Science” confirms that they have found the world’s first proto-feathers preserved in amber.  This shows that some small predatory dinosaurs that roamed southern Alberta about eighty million years ago were likely covered in proto-feathers, or alternatively, it provides tantalising evidence regarding the diversity of those Avian dinosaurs – the birds.

Palaeo-ecologist at the University of Alberta, Alexander Wolfe stated

“It gives us something we’ve never had before.  It gives us, for the first time, the opportunity to really study these proto-feathers in detail.”

Although scientists had previously found evidence pointing to the existence of proto-feathers, this is the first time they have been found preserved in amber, Wolfe went onto say.

Canadian Fossils

Although, as far as we at Everything Dinosaur know, there have been no fossils of feathered dinosaurs discovered to date in Alberta.  Preservation conditions have to be very special indeed to permit the fossilisation of such fine and delicate structures.  However, such conditions existed in the Cretaceous of northeastern China (Liaoning Province) and some remarkable specimens have been excavated here.  Many fossils of small, cursorial theropods have been found, along with thousands of fossils of birds.  One of the most amazing feathered dinosaur fossils is “Dave” a fossil of a small dinosaur known as Sinosauropteryx (Sinosauropteryx prima), which had halos of black fuzz surrounding its fossil, these have been interpreted as being feather-like structures, probably helping to insulate and keep this active, endothermic creature warm.

A Replica of the Feathered Dinosaur Sinosauropteryx

PNSO Sinosauropteryx dinosaur model.

PNSO Yuyan the Sinosauropteryx dinosaur model.

In pictures of Sinosauropteryx fossil material, the close-up view of the head and neck of a Sinosauropteryx shows the strange, feather-like structures.  Some scientists refused to believe that these were feather-like filaments.  Some argued that this was evidence of organic residue from the fossilisation process or a continuous crest of skin that ran down the spine of the animal.  However, more feathered dinosaur fossils have been found, including more specimens of Sinosauropteryx and the feathered dinosaur theory is now widely accepted.

Commenting on the difference between the Canadian amber fossils and the Chinese specimens, Wolfe stated:

“You can’t really see them [the feathers] with anywhere near the kind of details with which we can see these structures in amber.  Essentially these things are mummified in the plant resin, and it’s incredibly stable and it’s incredibly tough.  So we actually have these organic remains, the structures in amber have been trapped for 80 million years and haven’t been transformed chemically or visually to any degree.”

Tiny Proto-feathers

The proto-feathers – single strands or clumped bunches of strands – most likely came from small theropod dinosaurs that thrived during the Late Cretaceous. Theropods are the group of dinosaurs most closely related to today’s birds, and include large predators such as Daspletosaurus torosus and small, stealth hunters that probably lived in the undergrowth avoiding the attentions of their larger, fearsome cousins, dinosaurs such as Troodon, (T. formosus).

Wolfe added:

“Nothing even comparable to that exists in modern birds today.”

The tiny proto-feather strands would have become stuck on sap when dinosaurs bumped up against trees at a time when southern Alberta was a lush, swampy, forest lowland, located west of the shore of the western interior sea, a shallow, warm ocean that extended from the Arctic to Texas effectively isolating eastern North America from the west.  The tree sap containing the primitive proto-feathers became fossilised, turning into amber, which is often found in coal in Alberta, especially around the Taber and Grassy Lakes areas.

Along with the preserved proto-feathers, the researchers found more highly evolved feathers from the same time period.  These finds include downy feathers from diving birds as well as flight feathers.  Although the scientists cannot be certain that some of the feather-like structures once adorned the hides of dinosaurs, these fossils provide tantalising evidence and certainly raise that possibility.

One of the research team members added:

“We would not have predicted to have such a broad evolutionary range of feather adaptations and feather morphological specialisations, everything from flight to insulation to water retention and diving.  We would not have expected to find this all together.”

It was University of Alberta palaeontology graduate student Ryan McKellar who first started looking for bits of feather trapped in amber about four years ago, while searching samples for preserved insects.  The tiny amber samples, most just a few millimetres long, came from several collections, including from the Royal Tyrrell Museum, the University of Alberta and from amateur collectors in the Medicine Hat area.

Ryan commented:

“We’re very excited about the find.  It’s a truly unique snapshot of what was going on in some of these Cretaceous ecosystems.  It paints a picture where, basically, you’ve got dinosaurs such as theropods with fuzzy or hair-like plumage alongside birds with relatively advanced feather structures, in the same forest at the same time, about eighty million years ago.”

Only about one in fifty amber samples contain any biological material, McKellar added, who recently finished his thesis and is now a palaeontologist doing postdoctoral work at the University of Alberta.  Out of 4,000 amber samples that did contain biological material, the University of Alberta team found a total of eleven containing evidence of feathers.

Such fossils are incredibly rare, the researchers examined over 200,000 pieces of amber to find just eleven examples of fossilised feather material.

The feather strands are so well preserved that researchers can see micron-scale structures on them, as well as pigments, this may help palaeontologists piece together the organic structures that reveal what colour the dinosaurs with feathers may actually have been.  This adds a new and exciting dimension to the University of Manchester (England) team’s work as they use powerful scanning computers to interpret minute organic molecules that could preserve some record of the colour of theropod dinosaurs.

To read more about Manchester University’s study: Taking the Bio-Synthetic Pathway.

An article on the findings, written by McKellar, Wolfe, palaeontologist Brian Chatterton and renowned dinosaur expert Philip Currie, is published this week in “Science”.

This paper explains that up until very recently, extinct dinosaurs were considered to be all covered in scales, just like crocodiles are today.  Very few fossils of primitive birds (stem avians) were known until the Liaoning deposits were explored.  However, over the last twenty years or so much as changed.  From a re-examination of Archaeopteryx (A. lithographica) to the establishment of the evolution of feathered creatures that dates back to the Middle Jurassic  Feathered animals abound and extend deep into non Avian history, even, perhaps, to basal dinosaurs. Now, instead of scaly animals portrayed as usually drab creatures, we have solid evidence for a fluffy, coloured past.

Next Wednesday, the BBC television series “Planet Dinosaur” focuses on the amazing feathered dinosaur discoveries of north-eastern China.  Viewers will be able to see amazing theropod dinosaurs such as Microraptor (Microraptor gui) a feathered dinosaur that to all intents and purposes could fly and to meet miniature feathered predators such as Sinornithosaurus (S. millenii) with its potentially poisonous bite.

For models and replicas of Late Cretaceous feathered dinosaurs and other theropods: Feathered Dinosaur Models and Other Prehistoric Creatures.

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