Rare fossils of feathered dinosaurs show the link between these ancient creatures and birds.

Do you ever wonder how birds evolved to look the way they do today?

Well, it’s actually a long-debated topic. One of the major sticking points in this discussion is that feathers, a major evolutionary characteristic of birds, are fragile and therefore rarely preserved in the fossil record.

Before such evidence was recovered, it was difficult to unravel the ancestry of these winged creatures. But that all changed in the nineteenth century, when a fossil was discovered which linked modern birds to their ancient, evolutionary ancestors: the dinosaurs.

The fossil was an Archaeopteryx, a primitive bird-like dinosaur. While it exhibited many dinosaur- and reptile-like features, it also clearly displayed an imprint of feathers along its arm. Since feathers are entirely unique to birds, finding a fossilized dinosaur with them suggested a connection between these two groups of creatures.

From there, even more feather types, like quills and down, were found in the fossil record; with each discovery, new light was shed on the evolutionary story of the feather.

Some of the most groundbreaking finds occurred in the 1990s in the Liaoning province of northeastern China. Here Chinese scientist Xing Xu discovered a variety of feathered theropod dinosaur fossils.

These specimens were game changing because of the manner in which they were preserved; the animals had been smothered by ash during a volcanic eruption, perfectly burying their bodies and preserving the feathers.

From these incredible fossils, we learned a key fact: feathers developed in stages. They started out as simple unbranched quills that gradually grew in complexity and eventually became the much more complicated, asymmetric flight feathers – the type we now recognize.

Not just that, but at each intermediary stage of development, it became clearer that the dinosaurs who bore these feathers were the evolutionary ancestors of modern birds.

Now that we know how birds got their feathers, we’ll learn how they began to fly.