Enantiornithines, a group of toothed birds dating from the Cretaceous period, are considered by scientists to be very well understood thanks to an extensive fossil record. But a recent discovery has challenged previous assumptions and provided new insight into the life and evolution of these birds.

A group of Chinese scientists led by Dr. Lida Xing, a paleontologist at the China University of Geosciences in Beijing, discovered a set of 99-million-year-old baby Enantiornithine wings encased in amber for sale in an amber market in Myanmar. The wings were remarkably well-preserved, with feathers, flesh and bone still present—a phenomenon that rarely occurs in common compression fossils—providing the researchers with a unique opportunity to delve deeper into the history of these creatures.  

Canadian Geographic spoke to Ryan McKellar, a colleague of Dr. Xing and curator of invertebrate paleontology at the Royal Saskatchewan Museum, to learn more about this amazing discovery.

What is so significant and unique about this particular discovery?

We have a really good record of these birds, but mostly in the form of compression fossils. This type of fossil is limiting because the bird is squished flat and stuck in sedimentary rock, so we are lucky if we get to see feathers preserved at all. With this particular discovery, the amber has allowed us to see the wings in 3D with a new level of detail. We’ve been able to study the finer structure of the feathers and their pigmentation, and we have been able to study the skin, the bone in 3D, and some of the structure inside the bone. One especially exciting aspect was being able to see the distribution of the feathers on the wing, and learning how structurally similar the Enantiornithine feathers are to modern bird feathers. 

What have you learned from studying these wings?

The wings have confirmed a lot of the earlier work done based on compression fossils. We now know for sure that as hatchlings, these birds had feathers almost identical to modern bird adult feathers; basically, they skipped the downy feather stage most people associate with chicks.

In terms of what’s new, we have been able to see colouration for the first time. These wings were a walnut-brown on the top surface with a spotted banding pattern ideal for camouflage, and white on the bottom surface. We also know that once these birds hatched they were almost immediately equipped to fly and crawl around on tree branches.

How did these two particular birds die?

It seems that one of the birds was actually entombed in the resin while it was still alive, based on the fact that when you look in the amber you can actually see claw marks on the resin. The other specimen’s wings were more dried out and a piece of the wing had clearly been snapped off, suggesting it had been attacked by a predator. So definitely some struggle marks for both birds.

What was life like 99 million years ago, when these birds lived?

This was the mid-Cretaceous era, so there will still dinosaurs around and a lot of birds. This was also the time when flowering plants were starting to take over from conifers, and when a lot of the insects we know of today (beetles, flies, wasps, etc.) were starting to diversify.  

What will happen with the wings now?

They are currently in China and will continue to be treated as research specimens, eventually making their way into a museum exhibit.