Paleontologists have traced birds’ origins back to a group of small, nonflying theropod dinosaurs known as maniraptorans. The first feathered dinosaurs didn’t fly; their feathers were just for body insulation or possibly for display. The earliest known flying bird is Archaeopteryx, and birds evolved into a wide range of sizes and shapes by the time of the end-Cretaceous mass extinction, which eliminated the rest of the dinosaurs. Fortunately, some bird groups survived—and they’re the source of all living bird species. Since there are now thousands more species of birds than there are of mammals, you could say that dinosaurs still dominate Earth today.

One of a dozen examples of the oldest known flying bird, the “Berlin specimen” of Archaeopteryx lithographica displays well developed wing feathers, with which the toothed bird flew 155 million years ago.

The early Cretaceous compsognathid Sinosauropteryx prima had downy protofeathers on its head and body. Found by a farmer in Liaoning, China, this was the first discovery of a feathered dinosaur.

The maniraptoran Caudipteryx zoui was among the first dinosaurs to have well-developed feathers, including a tail plume.

Among the earliest birds with a toothless beak, Confuciusornis dui links Archaeopteryx to more modern birds.