Or that chickens and turkeys have experienced fewer gross genomic changes than other birds as they evolved from their dinosaur ancestor?

Wondered why hens lost their teeth, why penguins have a thick skin and how the peacock got its tail?

The most ambitious genetic study ever undertaken on bird evolution has found that almost all modern birds diversified after the dinosaurs became extinct 66 million years ago.

An international collaboration of scientists worked for four years to sequence, assemble and compare the full genomes of 48 bird species representing all major branches of modern birds including the crow, duck, falcon, parakeet, crane, ibis, woodpecker and eagle.

It is the largest whole genomic study across a single vertebrate class ever undertaken.

The study made connections they didn't know existed before.

The work revealed how vocal "learning" of songs evolved in songbirds and shows that many of the genes involved in that learning are similar to humans.

"The popular view until now has been that the extraordinary diversity of birds began during the dinosaur age but we found little support for this," said Simon Ho from the University of Sydney. He added "Our data helped solidify the surprising notion that parrots and songbirds are sister groups in the tree of life of birds, so their shared ability to learn songs — in the case of parrots, human speech sounds — likely had a common origin. In contrast, hummingbirds are separate, so their ability to learn songs — yes, hummingbirds sing and learn how to sing from their parents — arose separately in evolution,"

The Avian Phylogenomics Consortium involves more than 200 scientists hailing from 80 institutions in 20 countries, including the BGI, the University of Copenhagen, Duke University, the University of Texas at Austin, the Smithsonian Museum, the Chinese Academy of Sciences, Louisiana State University and many others.

Previous attempts to reconstruct the avian family tree using partial DNA sequencing or anatomical and behavioral traits have met with contradiction and confusion.

Because modern birds split into species early and in such quick succession, they did not evolve enough distinct genetic differences at the genomic level to clearly determine their early branching order, the researchers said.

To resolve the timing and relationships of modern birds, the consortium authors used whole-genome DNA sequences to infer the bird species tree.

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

For example, the findings support three independent origins of water birds. They also indicate that the common ancestor of core land birds, which include songbirds, parrots, woodpeckers, owls, eagles and falcons, was an apex predator, which also gave rise to the giant terror birds that once roamed the Americas.

Based on this new genomic data, only a few bird lineages survived the mass extinction. They gave rise to the more than 10,000 Neoaves species that comprise 95% of all bird species living with us today. The freed-up ecological niches caused by the extinction event likely allowed rapid species radiation of birds in less than 15 million years, which explains much of modern bird biodiversity.

With about 14,000 genes per species, the size of the datasets and the complexity of analyzing them required several new approaches to computing evolutionary family trees.

The team from the University of Kent found that the chicken has the most similar overall chromosome pattern to its avian dinosaur ancestor.

The researchers also found that the fastest rate of change had occurred in the zebra finch and budgerigar, consistent with more rapid speciation events in songbirds and their relatives.

From the whole chromosome level to the order of genes, this group found that the genomic structure of birds has stayed remarkably the same among species for more than 100 million years. The molecular evolution rate across all bird species is also slower compared to mammals.

Just as the sex of humans is determined by the X and Y chromosomes, the sex of birds is controlled by the Z and W chromosomes. The W makes birds female, just as the Y makes humans male. This group also found that bird species are at drastically different states of sex chromosome evolution. For example, the ostrich and emu, which belong to one of the older branches of the bird family tree, have sex chromosomes resembling their ancestors. Yet some modern birds such as the chicken and zebra finch have sex chromosomes that contain few active genes.

So how did birds lose their teeth? The evidence suggests that five tooth-related genes were disabled within a short time period in the common ancestor of modern birds more than 100 million years ago.

When did colorful feathers evolve? Elaborate, colorful feathers are thought to be evolutionarily advantageous, giving a male bird in a given species an edge over his competitors when it comes to mating. Scientists found that genes involved in feather coloration evolved more quickly than other genes in eight of 46 bird lineages. Waterbirds have the lowest number of beta keratin feather genes, landbirds have more than twice as many, and in domesticated pet and agricultural bird species, there are eight times more of these genes.

The consortium also answered an interesting question? How do penguins adapt to the cold and hostile Antarctic environment? They now say that penguins have many distinct morphological features that different with other birds. They are flightless, with specialized wings and skin. Through sequencing the genomes of Adelie and emperor penguins, researchers have revealed the genetic basis of adaptations related to their feathers, wings, eyes and lipid metabolism. They have also revealed their historical population changes in response to climate change and glaciation, and estimated that the current species of penguins first appeared around 60 million years ago.