The archeopteryx is a Jurassic avian dinosaur, currently understood to be the first bird.

They were roughly magpie sized and had feathers, but unlike modern birds

they had teeth and skeletal tails. Archaeopteryx was a notable find

because it was discovered soon after Darwin's "On the Origin of Species" was published,

helping verify his then controversial theory of evolution by demonstrating an

evolutionary ancestor to birds.

Text source, image source