An enormous asteroid crashed into the Earth about 65 million years ago. While terrestrial dinosaurs like the famed Tyrannosaurus rex were wiped out, many avian animals really began to flourish. Considering that there are more than 10,000 species of birds on Earth, flourish may even be an understatement. Keeping birds organized in a neat family tree is a bit of a Herculean task, since there are so many species and their evolution has been a little unclear. However, some advances in genomic sequencing and analysis are beginning to create a more lucid picture of how the planet’s living dinosaurs evolved.
In two studies published April 1 in the journals Proceedings of the National Academy of Sciences (PNAS) and Nature, scientists reveal that a genetic event about 65 million years ago has misled them about the true history of avian evolution. A section of one chromosome hasn’t mixed together with nearby DNA as it should have. This section is only tiny fraction of the bird genome, but was enough to make it difficult for scientists to build a more detailed bird family tree. Â
A sticky chunk of DNA
In 2014, advances in computer technology used to study genomes helped scientists piece together a family tree for the Neoaves. This group includes the majority of bird species. Using the genomes of 48 species, they split the Neoaves into two major categories. Doves and flamingos were in one group and all the other bird species belonged to the other group.Â
When a similar genetic analysis was repeated using 363 bird species for this new study, the team saw a different family tree emerge. This one points to four main groups and reveals that flamingos and doves are more distantly related and it all came back to a specific spot in the chromosomes.
[Related: Birds are so specialized to their homes, it shows in their bones.]
Within these two family trees, the team looked for explanations that could tell them which one was correct. They found one…
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