Rare fossil bird deepens mystery of avian extinctions

• 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. 
• The fossil's breast bone or sternum, where flight muscles attach, is more deeply keeled than other enantiornithines, implying a larger muscle and stronger flight more similar to modern birds.

SOURCE : SCIENCE DAILY