New insights into the origin of birds

Mark Puttick and colleagues investigated the rates of evolution of the two key characteristics that preceded flight: body size and forelimb length. In order to fly, hulking meat-eating dinosaurs had to shrink in size and grow much longer arms to support their feathered wings.

"We were really surprised to discover that the key size shifts happened at the same time, at the origin of Paraves," said Mr Puttick of Bristol's School of Earth Sciences. "This was at least 20 million years before the first bird, the famous Archaeopteryx, and it shows that flight in birds arose through several evolutionary steps."

Being small and light is important for a flyer, and it now seems a whole group of dozens of little dinosaurs were lightweight and had of one sort or another. Most were gliders or parachutists, spreading their feathered wings, but not flapping them.

"Out of all these flappers and gliders, only the birds seem to have been capable of powered flight," said co-author Mike Benton, Professor of Vertebrate Palaeontology at Bristol.

"But you wouldn't have picked out Archaeopteryx as the founder of a remarkable new group."

The study applied new numerical methods that calculate the rate of evolution of different characteristics across a whole evolutionary tree, and identify where bursts of fast evolution occurred.

"Up to now you could only have guessed roughly where the major evolutionary transitions occurred," said Dr Gavin Thomas of the University of Sheffield, "but the new methods pinpoint the size changes. The small size of birds and their long wings originated long before birds themselves did."

Birds owe their success to their flight, wings and feathers. Until the 1990s, when the first feathered dinosaurs were found in China, birds were thought to have originated rapidly, marking a major transition from dinosaurs. Now, we know that Archaeopteryx was only one of a large number of small, flying .

"The origin of birds used to be seen as a rapid transition," said Mark Puttick, "but now we know that the key characteristics we associate with them arose much earlier."

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How birds got their wings: Fossil data show scaling of limbs altered as birds originated from dinosaurs

Citation: New insights into the origin of birds (2014, February 23) retrieved 24 August 2019 from
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Feb 23, 2014
Those large jumps are being filled in constantly across multiple species just look up the last five years of whale fossil discoveries.
"Any logical person" would think major changes might often take some time. Adapt or die.
Do some reading on DNA and the three forms of life on this planet. The fact is we are in the family of Eukaryote even though we have 10X more microbes from the other houses Bacteria, and Archaea" living in and on us. The human Biome concept is mind blowing if you take the time to learn about it. In this family we are related to all other animals, plants and fungi.
Nice to have a big family!

Feb 24, 2014
Time to have another look at McCarthy's tweak to neo-Darwinian thinking.
Hybridization and stabilization.

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