Modern birds are essentially living dinosaurs with skulls that are remarkably similar to those of baby dinosaurs, according to a new Harvard study.
The study — titled "Birds have paedomorphic dinosaur skulls" and published online in the journal Nature — found evidence that the origins and evolution of modern birds are the result of a drastic change in dinosaur development known as "progenesis" that caused birds to reach sexual maturity sooner.
Species of birds take as little as 12 weeks to reach sexual maturity, thereby retaining the physical characteristics of baby dinosaurs into adulthood.
"By changing the developmental biology in early species, nature has produced the modern bird – an entirely new creature – and one that, with approximately 10,000 species, is today the most successful group of land vertebrates on the planet," Harvard associate professor and lead researcher Arkhat Abzhanov said in a press release.
The researchers noted that it has been traditionally difficult to explain the evolution of certain characteristics of birds (such as feathers, flight and wishbones), but the realization that skulls of modern birds and those of young dinosaurs are similar inspired the study.
Consequently researchers analyzed fossil evidence from skeletons, eggs and soft tissue of bird-like dinosaurs and primitive birds from up to 250 million years ago while tracking how the skull changed shape over millions of years.
They found that modern birds "are living theropod dinosaurs, a group of carnivorous animals that include Velociraptor," according to co-author Mark Norell.
The authors hailed the study as a terrific achievement in the understanding of the mechanisms that drive evolutionary biology.
"That you can have such dramatic success simply by changing the relative timing of events in a creature's development is remarkable," Abzhanov said. "We now understand the relationship between birds and dinosaurs that much better, and we can say that, when we look at birds, we are actually looking at juvenile dinosaurs."
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