How did birds evolve?

For more than a century, Archaeopteryx was the earliest known bird genus, and the only one known from the Jurassic period, when birds first evolved. Last year, fossils of a newly discovered genus revealed that Archaeopteryx wasn’t alone: a creature called Baminornis also walked the Jurassic Earth — and flew as well. These two genera of birds are so different that some researchers suggest that the first birds predated them both. The findings are revealing clues about how and why birds evolved, and hint that the evolutionary story of birds has an even earlier chapter than researchers thought.