Archaeopteryx is a fossil bird that lived during the late Jurassic period, approximately 150 million years ago. It is considered to be the earliest known bird, and is an important link between modern birds and their dinosaur ancestors. Archaeopteryx had features of both birds and dinosaurs, including feathers, wings, and claws on its wings. It is one of the most famous fossils in the world, and is an important part of the fossil record.