Study uncovers influence of Earth's history on the dawn of modern birds

December 11th 2015

House finch Credit: Wikimedia Commons

New research led by the American Museum of Natural History reveals that the evolution of modern birds was greatly shaped by the history of our planet's geography and climate. The DNA-based work, published today in the journal Science Advances, finds that birds arose in what is now South America around 90 million years ago, and radiated extensively around the time of the Cretaceous-Paleogene extinction event that killed off the non-avian dinosaurs. The new research suggests that birds in South America survived this event and then started moving to other parts of the world via multiple land bridges while diversifying during periods of global cooling.

"Modern birds are the most diverse group of terrestrial vertebrates in terms of species richness and global distribution, but we still don't fully understand their large-scale evolutionary history," said Joel Cracraft, a curator in the Museum's Department of Ornithology and co-author of the paper. "It's a difficult problem to solve because we have very large gaps in the fossil record. This is the first quantitative analysis estimating where birds might have arisen, based on the best phylogenetic hypothesis that we have today."

Cracraft and lead author Santiago Claramunt, a research associate in the Museum's Department of Ornithology, analyzed DNA sequences for most modern bird families with information from 130 fossil birds to generate a new evolutionary time tree.

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Modern Birds Took Flight 95 Million Years Ago

by Laura Geggel, Staff Writer | December 11, 2015 03:30pm ET

Modern birds — from the soaring eagle to the tiny hummingbird — share a common ancestor that lived about 95 million years ago in South America, a new study finds.

That feathery common ancestor laid the groundwork for its innumerable descendants. When an asteroid hit the Yucatan Peninsula about 66 million years ago, it killed off the nonavian dinosaurs. So-called modern birds in South America survived and rapidly diversified, the researchers said.

These modern South American birds then moved to other parts of the world via land bridges (even fliers need stopovers on land), diversifying during periods of global cooling, the researchers found.

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The evolution of modern bird species revised by major new study

Great Spotted Woodpeckers are one species said to have descended from an apex predator

The genomes of modern birds reveal how they emerged and evolved after the mass extinction that wiped out dinosaurs 66 million years ago, reports Smithsonian Science.

The family tree of modern birds has long been the subject of debate and the evolution of our more than 10,000 species has not been known.

Now a four-year international collaboration involving more than 200 scientists from 80 institutions in 20 countries has sequenced, assembled and compared full genomes of 48 bird species.

The first findings of the Avian Phylogenomics Consortium led by Guojie Zhang of the National Genebank at BGI in China and the University of Copenhagen, Erich D Jarvis of Duke University and the Howard Hughes Medical Institute and Thomas P Gilbert of the Natural History Museum of Denmark, suggests some remarkable new ideas about bird evolution.

The consortium focused on species representing all major branches of modern birds including the crow, duck, falcon, parakeet, crane, ibis, woodpecker and eagle.

The first flagship paper published in Science presents a new family tree for birds, based on whole-genome data.

The new family tree resolves the early branches of Neoaves (new birds) and supports conclusions about some relationships that have been long-debated.

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Birds descended from gliding dinosaurs — evidence mounts

Evidence is mounting that modern birds descended from gliding, feathered non-avian dinosaurs.

Two dinosaurs could be candidates for the bottom of the bird family tree, and each helps to reveal how feathers first evolved.

"The oldest known feathered dinosaurs would be Anchiornis (155 million years ago) and Epidexipteryx (between 152 million and 168 million years ago)," Yale University paleontologist Nicholas Longrich told Discovery News. "Feathers seem to have appeared initially for insulation. Basically they start out as down, and later are used to make wings."

For a study published in the latest Current Biology, Longrich and colleagues Jakob Vinther and Anthony Russell examined fossils of Anchiornis huxley and of Archaeopteryx lithographica, a Jurassic species that could be the world's oldest known bird.

"Where dinosaurs end and birds begin is a bit arbitrary," Longrich explained. "There's no clear cutoff that separates one from the other. That's the nature of evolution; things gradually change from one thing into another."

The scientists found that the wing feathers of Archaeopteryx and Anchiornis were similar, but not identical. The variations between the two appear to represent early experiments in the evolution of the wing.

Continued:  http://www.msnbc.msn.com/id/49920250/ns/technology_and_science-science/#.UK6ARORp2Z8