"Bird Big Bang"

Birds Evolved in 'Big Bang,' New Family Tree Reveals (December 11, 2014)
Bird family secrets
In the new project, the researchers analyzed the genomes of 48 bird species (including 45 that had not been sequenced before), representing all major branches of birds, including the crow, duck, falcon, parakeet, crane, ibis, woodpecker and eagle. About 95 percent of today's birds belong to a group called Neoaves, and most of the species the researchers analyzed belong to this group.The new findings show that Neoaves underwent a "Big Bang" of evolution, with many new species appearing within just a few million years of the time that most dinosaurs went extinct about 66 million years ago.
Previous work had suggested a more gradual evolution of this group.
[...] Other findings based on the new research offer clues to how birds' sex chromosomes evolved, how birds came to lose their teeth, how birdsong regulates genes in the brain, as well as details about the common ancestor of birds and crocodiles."

Speaking of Archeopteryx,

"...These traits by themselves do little to help place the fossil in the dinosaur–bird transition, but Xu reports that it also has extremely long middle and last finger bones and a wishbone with an L-shaped cross-section at one end."

They've found some creatures who were birds distant cousins, and they went extinct... while the ancestors of bird led straight to a lineage that spawned birds.
That is, when the dinosaurs DIED OUT (see new genetic findings) birds suddenly diversified -- probably like an earlier article I posted about all modern cows descend from a small group of 80 (EIGHTY) aurochs which were domesticated some 10,000 years ago.
Hard to believe such a small population could populate the whole planet, isn't it?
Crocodiles and birds share a common ancestor and birds did not evolve from Cretaceous dinosaurs. They probably evolved in this "big bang" because the dinosaurs which were eating their buddies, went extinct when the Cretaceous came to an end.

Archaeopteryx no longer first bird
Archaeopteryx has long been placed at the base of the bird evolutionary tree. It has traits that have helped to define what it is to be a bird, such as long and robust forelimbs. Yet in recent years, the discoveries of numerous small, feathery dinosaurs have created a conundrum for palaeontologists, raising questions about which animals are the ancestors of modern birds and which are just closely related cousins.
The fossil that is driving the latest Archaeopteryx rethink is called Xiaotingia zhengi, and is described in Nature today1 by Xing Xu, a palaeontologist at the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing, and his colleagues. It was found in western Liaoning, China, in rocks dating to the Late Jurassic epoch, 161 million–145 million years ago. Like many similar fossils, it is surrounded by feather impressions in the rock, but has claws on the ends of its forelimbs and sharp teeth.
These traits by themselves do little to help place the fossil in the dinosaur–bird transition, but Xu reports that it also has extremely long middle and last finger bones and a wishbone with an L-shaped cross-section at one end. These characteristics, Xu argues, identify Xiaotingia as very closely related to Archaeopteryx and another feathery relative, Anchiornis.
After analysing the traits present in Xiaotingia and its relations, Xu and his colleagues are suggesting that the creatures bear more resemblance to the dinosaurs Velociraptor and Microraptor than to early birds, and so belong in the dinosaur group Deinonychosauria rather than in the bird group, Avialae. Many features led the team to this decision, but the most immediately noticeable are that Xiaotingia, Archaeopteryx and Anchiornis have shallow snouts and expanded regions behind their eye sockets. Microraptor has similar traits, but the early birds in Avialae have very different skulls..."
(Source)

The conclusions drawn from DNA, are profound.

Instead of T. Rex evolving into a chicken, or, Velociraptor evolving into a canary, Brontosaurus into a duck...

The immediate ancestors of birds were present.
The "common ancestor" (the archosaurian ancestor) of nearly all modern birds, was no longer around... and birds could not diversify until the dinosaurs -- were DYING OUT... 66 million years ago. When the dinosaurs were out of the picture, and stopped eating our sweet little feathered friends... Birds had their first chance to diversify and thrive, exploiting niches they had previously been forbidden access to. Birds diversified worldwide, when the dinosaurs disappeared. Which makes total sense.

"...researchers analyzed the genomes of 48 bird species (including 45 that had not been sequenced before), representing all major branches of birds, including the crow, duck, falcon, parakeet, crane, ibis, woodpecker and eagle.
About 95 percent of today's birds belong to a group called Neoaves, and most of the species the researchers analyzed belong to this group.The new findings show that Neoaves underwent a "Big Bang" of evolution, with many new species appearing within just a few million years of the time that most dinosaurs went extinct about 66 million years ago.
Previous work had suggested a more gradual evolution of this group."
(Source)

"...previous work suggested a more gradual evolution..."

The hypothesis, dreaming of T. Rexes transforming into a Chicken... and all sorts of dinosaurs transforming into birds, popping up here and there, into birds... all over the place at different phases anywhere from 100 million years ago to the last 65 million years ago and earlier! With all certainty that birds were pretty much diversified from Cretaceous dinosaurs all over the planet, and... many dinosaur ancestors.

The hypothesis is flawed. A slim, small... very narrow bird lineage, that spans back through bird ancestry, and this "Bird big bang" -- is marked when dinosaurs go extinct... around 66 million years ago. Competition for space was no longer a problem. No predators to consume those sweet birds. That is where the majority of "modern birds" come from, sharing a common ancestor in that time frame.
"Evolved from dinosaurs" explains absolutely nothing, because currently, they don't even know enough about dinosaurs to draw all the hopeful conclusions they have.

But we know birds are not cold-blooded reptiles -- nor "intermediate", and the modern varieties arose AFTER the dinosaurs, not along side them, not because of them... but because the dinosaurs went extinct.

During the age of the dinosaurs, when Archeaopteryx hatched its eggs, or a near cousin of Archeopteryx hatched an egg... and those primitive bird ancestors grew big enough to get into the air... dinosaurs snatched them up like a snack. T. Rex liked eating chicken. That's why birds did not evolve "from" the dinosaurs.
Birds evolved (and branched out and diversified) around 66 million years ago, when the dinosaurs were nearly extinct. Or so the genetic research seems to conclude.

Here's one clear advantage birds had over dinosaurs, which by itself is evidence that birds and dinosaur physiology was only distant in its relation.

Dinosaurs neither warm-blooded nor cold-blooded
Metabolic analysis suggests they could regulate body temperature, but only to a point.
Alexandra Witze, 12 June 2014
Dinosaurs were neither sluggish like lizards nor high-energy like mammals, but something in between, a study suggests.
The work stakes out a rare middle ground in the long-running debate over whether dinosaurs were ‘cold-blooded’ ectotherms, which use the environment to adjust their internal temperature, or ‘warm-blooded’ endotherms, which regulate their body temperature from within. “There’s a third way,” says John Grady, a biologist at the University of New Mexico in Albuquerque.
Today, that middle ground is occupied by animals including tuna, lamnid sharks and leatherback turtles. Studying how those creatures control their body heat might help to reveal how dinosaurs did it millions of years ago, Grady says. Mesotherms burn energy from within to regulate their body heat, but not to a constant temperature as a mammal or bird would do. Tuna, for instance, stay up to 20 °C warmer than the surrounding water, except when they dive deep into colder waters, when their metabolic rate can also plunge."
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(Source)