Influence of Earth's history on the dawn of modern birds

[Judi Lynn]

Influence of Earth's history on the dawn of modern birds

New time tree indicates that avian evolution was molded by climate change and plate tectonics

Date: December 11, 2015

Source:American Museum of Natural History

Summary:The evolution of modern birds was greatly shaped by the history of our planet's geography and climate. New research 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. The new research suggests that birds in South America survived this event and then moved around the world via multiple land bridges while diversifying during periods of global cooling.



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.

"With very few exceptions, fossils of modern birds have been found only after the Cretaceous-Paleogene (K-Pg) extinction," said Claramunt. "This has led some researchers to suggest that modern birds didn't start to diversify until after this event, when major competitors were gone. But our new work, which agrees with previous DNA-based studies, suggests that birds began to radiate before this massive extinction."

More:
http://www.sciencedaily.com/releases/2015/12/151211145038.htm

[jakeXT]

1. I'm still fascinated by quantum effects in the bird's eye

My third and final example is the most beautiful, wonderful idea. It's also still very speculative, but I have to share it with you. The European robin migrates from Scandinavia down to the Mediterranean, every autumn, and like a lot of other marine animals and even insects, they navigate by sensing the Earth's magnetic field. Now, the Earth's magnetic field is very, very weak; it's 100 times weaker than a fridge magnet, and yet it affects the chemistry -- somehow -- within a living organism. That's not in doubt -- a German couple of ornithologists, Wolfgang and Roswitha Wiltschko, in the 1970s, confirmed that indeed, the robin does find its way by somehow sensing the Earth's magnetic field, to give it directional information -- a built-in compass.

14:36
The puzzle, the mystery was: How does it do it? Well, the only theory in town -- we don't know if it's the correct theory, but the only theory in town -- is that it does it via something called quantum entanglement. Inside the robin's retina -- I kid you not -- inside the robin's retina is a protein called cryptochrome, which is light-sensitive. Within cryptochrome, a pair of electrons are quantum-entangled. Now, quantum entanglement is when two particles are far apart, and yet somehow remain in contact with each other. Even Einstein hated this idea; he called it "spooky action at a distance."

15:11
(Laughter)

15:13
So if Einstein doesn't like it, then we can all be uncomfortable with it. Two quantum-entangled electrons within a single molecule dance a delicate dance that is very sensitive to the direction the bird flies in the Earth's magnetic field.

15:25
We don't know if it's the correct explanation, but wow, wouldn't it be exciting if quantum mechanics helps birds navigate? Quantum biology is still in it infancy. It's still speculative. But I believe it's built on solid science. I also think that in the coming decade or so, we're going to start to see that actually, it pervades life -- that life has evolved tricks that utilize the quantum world. Watch this space.

https://www.ted.com/talks/jim_al_khalili_how_quantum_biology_might_explain_life_s_biggest_questions/transcript?language=en#t-871405