The ancestry of every bird alive today can be traced back to a single "Founding Feathered Father" that lived in South America 95 million years ago, according to a new study.
The common ancestor of living birds, described in the journal Science Advances, likely lived much later than previously estimated. Prior reports suggested that the founding bird lived up to 170 million years ago during the Jurassic Period.
Dinosaurs (that didn't evolve into birds) were still prevalent in South America 95 million years ago, yet the Founding Feathered Father would have been a standout.
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"This ancestor would have looked like a bird, not like a dinosaur, and might have been capable of full flight, like many other birds from the Late Cretaceous," co-author Joel Cracraft of the American Museum of Natural History's Department of Ornithology told Discovery News.
The "many other birds" he mentioned went extinct, however, with just the one South American species being a direct ancestor of today's birds.
For the study, Cracraft and colleague Santiago Claramunt, also from the AMNH, estimated the age of modern birds using molecular clocks calibrated with information obtained from 130 fossils representing all major bird families.
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While the genetic data strongly indicates when and where the bird ancestor lived, the precise identity of this species remains a great mystery, even with the new evidence.
"There are no good candidates for this common ancestor of modern birds," Cracraft said. "The avian fossil record of the Late Cretaceous of South America and West Antarctica is poor and fragmentary."
The researchers were, however, able to determine that the common ancestor lived in South America for at least 25 million years before major changes started to occur. Different species began to rapidly originate from the Founding Feathered Father. This branching off of species is known to biologists as diversification.
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"Rapid diversification around 66 million years ago has been interpreted as the effect of empty ecological niches left by the mass extinction (which killed off the dinosaurs and many other animals)," Claramunt said. "But our results show that rapid diversification began before the mass extinction event and coinciding with a long-term cooling trend at the end of the Cretaceous."
During this cooling trend, some members of the founding bird's population left South America. These birds, evolving into various different species along the way, reached Africa, Europe and Asia through North America. Early bird populations also made their way to Australia and to New Zealand through Antarctica.
The authors then believe that both environmental change and plate tectonics affected bird evolution. The latter happens in many ways, they explained. By connecting and disconnecting land, plate movements impact travel routes, even for flying animals. The resulting land formations can then affect climate, with topographical changes, such as the rise of mountains, influencing weather trends and temperatures.
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The findings have future implications, given that the researchers discovered diversification rates decrease during warming trends. This could also happen under human-caused global warming. Since we are reducing and fragmenting tropical forests, today's birds appear to have several strikes against them.
The period of time 95 million years ago, however, appears to have been a golden age for birds and bird-like animals. Recently, Peter Makovicky of Chicago's Field Museum and colleagues announced the discovery of a small South American dinosaur, Buitreraptor gonzalezorum, with a very bird-like appearance. The rooster-sized carnivore intriguingly dates to the same time period, and comes from the same general location, of the theorized founding bird.
Makovicky and other paleontologists now believe that flight evolved at least twice in such animals: in prehistoric dino raptors of the southern hemisphere, like B. gonzalezorum, and in actual birds.