The Chicago Archaeopteryx is only the 13th fossil of its kind known to be in existence. It was unveiled Monday to the media. Scientists at the museum said it's the earliest bird known to science ...

CHICAGO (WBBM NEWSRADIO) — Monday was a big day at the Field Museum, as officials unveiled what’s been called one of the most important fossils ever discovered: the archaeopteryx.

So far, the oldest-known bird fossil is the famous Archaeopteryx lithographica, discovered in 1861 just two years after the publication of Darwin's On the Origin of Species, but Archaeopteryx ...

This is because it was a dinosaur—one that evolved long after the first known bird, Archaeopteryx, split off from the dinosaur family tree. Earlier dinosaurs, common ancestors to both ...