Where Did the Cretaceous Birds Go?

As evidence continues to pile up supporting the theropod dinosaur-to-bird transition, the question has arisen: where did all of the Cretaceous birds that did not give rise to modern birds go?  Science Daily has this report:

Now a team of paleontologists led by Yale researcher Nicholas Longrich has provided clear evidence that many primitive bird species survived right up until the time of the meteorite impact. They identified and dated a large collection of bird fossils representing a range of different species, many of which were alive within 300,000 years of the impact.
"This proves that these species went extinct very abruptly, in terms of geological time scales," said Longrich. The study appears the week of Sept. 19 in the journal Proceedings of the National Academy of Sciences.

Aside: the next time I see a scientist use the word “prove” I am going to strangle them. Scientists don't prove anything. They provide support for a hypothesis or they reject a hypothesis.  Onward.  The common consensus about the dinosaur extinction is that it was, in large part, caused by a huge meteorite that fell to earth toward the end of the Cretaceous in the Yucatan Peninsula.

The crater reflecting this impact is 110 miles across and, while it probably wasn't the entire cause of the dinosaur extinction, it wiped out a good chunk of 'em.The article continues:

Yet modern birds are very different from those that existed during the late Cretaceous, Longrich said. For instance, today's birds have developed a much wider range of specialized features and behaviors, from penguins to hummingbirds to flamingoes, while the primitive birds would have occupied a narrower range of ecological niches. "The basic bird design was in place, but all of the specialized features developed after the mass extinction, when birds sort of re-evolved with all the diversity they display today," Longrich said. "It's similar to what happened with mammals after the age of the dinosaurs."

Another piece of the puzzle!