What Was the Earliest-known Bird?

The earliest-known bird was Archaeopteryx, a species that lived around 150 million years ago, during the late Jurassic period. Archaeopteryx was a small, feathered theropod dinosaur that had many bird-like characteristics, such as feathers and a wishbone (furcula), but also retained many reptilian features, such as teeth and a long bony tail.

Archaeopteryx was first discovered in 1861 in the Solnhofen limestone deposits in Germany. The well-preserved fossils of Archaeopteryx show that it had fully formed flight feathers and a wing structure similar to that of modern birds, suggesting that it was capable of powered flight. However, the structure of its legs and feet also suggest that it may have been able to run and climb, and it probably had a terrestrial lifestyle.

Archaeopteryx is considered to be a transitional fossil between birds and dinosaurs, and it provides important evidence for the evolution of birds from small, feathered theropod dinosaurs. The discovery of Archaeopteryx was a key piece of evidence in the development of the theory of evolution and it is still considered one of the most important fossils in the history of paleontology.

It is worth noting that as paleontological research continues, new discoveries of early birds are being made and some of the earliest bird-like dinosaurs known have been dated to be even older than Archaeopteryx. For example, the bird-like dinosaur Aurornis xui, which lived about 160 million years ago, is considered the oldest bird known, but some studies suggest it's not a bird but a bird-like dinosaur.