Today’s birds descend from a small number of bird species living before the dinosaur extinction. Some of the birds that went extinct, the enantiornithines, were actually more common than and out-competed modern bird ancestors. Analysis of a newly described fossil, the most complete known from the Americas, demonstrates, too, that the enantiornithines were as agile and strong in flight as the ancestors of modern birds. Why, then, did enantiornithines die out and modern birds flourish?
Fossilized wishbone or furcula of Mirarce eatoni . The V shape is more like the wishbones of today’s birds, which are agile, strong fliers, than the U-shaped wishbones of theropod dinosaurs.
Credit: David Strauss photo