Archaeopteryx is a genus of bird-like dinosaurs that lived during the Late Jurassic period, roughly 150 million years ago, in the western part of Europe. By the Late Cretaceous, 70 million years later, true birds had evolved.

The name derives from the ancient Greek archaīos, meaning "ancient", and ptéryx, meaning "feather" or "wing".

It was roughly the size of a raven, with broad wings that were rounded at the ends and a long tail compared to its body length. Despite its small size, broad wings, and inferred ability to fly or glide, Archaeopteryx had more in common with other small Mesozoic dinosaurs than with modern birds. In particular, it shared the following features with the dromaeosaurids and troodontids: jaws with sharp teeth, three fingers with claws that moved independently (unlike the fused fingers of living birds), a long well-developed tail, and hyperextensible second toes or "killing claws".

The initial discovery was a single fossilized feather, unearthed in 1860 or 1861 and described in 1861 by Hermann von Meyer. It is currently located at the Natural History Museum of Berlin. The first skeleton, known as the London Specimen (BMNH 37001), was unearthed later that year near Langenaltheim, Germany.

Like the "raptors" in Steven Spielberg's Jurassic Park, the closely-related Archaeopteryx had a curved killing-claw on the second toe of each foot. These digits were hyperextendible, meaning that they could be held high off the ground to keep the tips sharp and ready for action.

In 2011, graduate student Ryan Carney and colleagues performed the first color study on an Archaeopteryx specimen. Using scanning electron microscopy technology and energy-dispersive X-ray analysis, the team was able to detect the structure of melanosomes in the isolated feather specimen described in 1861. The resultant measurements were then compared to those of 87 modern bird species, and the original color was calculated with a 95% likelihood to be black.

In 2004, scientists analyzing a detailed CT scan of the braincase of the London Archaeopteryx concluded that its brain was significantly larger than that of most dinosaurs. The reconstruction showed that the regions associated with vision took up nearly one-third of the brain. Other well-developed areas involved hearing and muscle coordination. These characteristics taken together suggest that Archaeopteryx had the keen sense of hearing, balance, spatial perception, and coordination needed to fly.

The type specimen of Archaeopteryx was discovered just two years after Charles Darwin published On the Origin of Species. The discovery seemed to confirm Darwin's theories, and it has since become a key piece of evidence for the origin of birds, the transitional fossils debate, and confirmation of evolution.

It is known to have evolved from small carnivorous dinosaurs, as it retains many features such as teeth and a long tail. It also retains a wishbone, a breastbone, hollow thin-walled bones, air sacs in the backbones, and feathers.

It was a carnivore and most likely ate smaller dinosaurs, mammals, insects, and potentially fish.