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Scientists map 48 bird genomes, unlocking their dinosaur pasts

A birds-eye view of the bird family genome. (AAAS/Carla Schaffer)

If you feel like your science news has been invaded by birds today, it's not your imagination: The journal Science published a series of papers (like, a whole bunch) dedicated to our feathered friends, and for good reason.

The flagship study of the bunch announces that 48 birds (at least one from every major bird lineage) have now had their entire genetic code uncovered. Until now, scientists only had a handful of common birds to work with. This massive increase in data has allowed researchers to uncover new information about the evolutionary origin of birds, the genes and brain mechanisms that drive their behavior, and their relationships to each other.

In other words, scientists pretty much just completed the bird family tree.

And that's a tricky tree to plant. Birds, which are the most species-rich class of four-limbed vertebrates, are the surviving descendants of dinosaurs. But understanding why birds survived while other dinos didn't -- and how they got to be such a diverse class of animals -- has long been a mystery. Modern birds split into different species many millions of years ago, so it's hard to pinpoint when and how they diverged from common ancestors.

But this glut of studies is the first solid step in solving that mystery. In one paper, for example, scientists used modern genomes to reconstruct the genome of an ancient organism -- the last common ancestor of crocodiles, birds, and dinosaurs.

Crocodiles, which have evolved very slowly, are actually more closely related to dinosaurs and birds than to other living reptiles. Once they had the new information from birds, researchers were able to piece together what a common ancestor would have looked like -- or what its DNA would have looked like, anyway. This will help scientists study past and present animals of that branch of the tree of life.

And the new genomic data helps tell the story of how birds survived the mass extinction of the other dinosaurs, too: Some have suggested that birds separated into many different species some 10 million years before the mass extinction that killed dinosaurs, but these studies suggest that the species boom occurred after. It's likely that a small number of birds survived the extinction, the researchers report. With so many evolutionary niches left empty by newly-extinct animals, birds were able to evolve into a wild collection of different species.

The genome mapping effort, which has resulted in eight papers this week in Science and another 20 in other journals, took the work of 200 people from 80 labs and several months of data-crunching with a super-computer. Read more about a couple great highlights -- what human speech and birdsong have in common, and how birds lost their teeth.

This Animation by Carla Schaffer of the American Association for the Advancement of Science illustrates major branches of the avian tree of life. (Video: AAAS/Carla Schaffer)