The dinosaurs were a large group of animals that first appeared in the fossil record about 227 million years ago. Then, about 65 million years ago, most of the dinosaurs went extinct, but one group– the birds– continues to thrive. The era during which the non-avian dinosaurs lived is called the Mesozoic. The Mesozoic is divided into three periods called the Triassic, Jurassic, and Cretaceous; the bird-like dinosaurs didn't appear until the Jurassic, and they continued into the Cretaceous. Scientists argue about whether feathers evolved at the same time as the dinosaurs, or whether the first feathers appeared on the first bird-like dinosaurs during the Jurassic. It seems likely that the early dinosaurs had primitive feather-like structures, but that fully developed feathers didn't appear until later.

Feathered dinosaurs have played an important role in the history of science. The first feathered dinosaur ever discovered was called Archaeopteryx (which means 'ancient bird'). Archaeopteryx was discovered in 1860, just two years after Darwin published On the Origin of Species, and its discovery was hailed as a stunning confirmation of Darwin's theory. At the time, dinosaurs were considered a kind of reptile, so Archaeopteryx was considered a transitional form between reptiles and birds. Since then over one hundred bird-like dinosaurs have been discovered, and scientists consider both Archaeopteryx and microraptor to be members of a large group of bird-like dinosaurs.

In more recent years, a number of dinosaur feathers have been discovered, mainly in China. Almost all of these feathers have been found on a particular kind of two-legged dinosaur known as coeleurosaurian theropods. In addition to Microraptor and Archaeopteryx, this group contains two very famous dinosaurs– Velociraptor and Tyranosaurus rex. Naturally, scientists wonder whether Velociraptor or Tyranoaurus had feathers. So far, no fossilized feathers have been found for either of these large dinosaurs, but there are good reasons to suspect that someday such feathers may be found. In fact, small bumps found on the bones in Velociraptor's arm bones suggest they may have had very large and powerful feathers. Even if these large dinosaurs had feathers, given their weight, it is extremely unlikely that they could have flown. Still, feathers are used for lots of things besides flight. They keep birds warm, help them camouflage, and are often used in courtship displays. Given all these uses, its not surprising that feathers come in so many different colors.

Interested in learning more about feathers? Watch the TED Ed lesson: How did feathers evolve? Carl Zimmer.