Researchers from Harvard University, The University of Texas at Austin and elsewhere have found evidence that the evolution of birds is the result of a drastic change in how dinosaurs developed. Scientists have long understood that modern birds descended from dinosaurs. Rather than take years to reach sexual maturity, as many dinosaurs did, birds sped up the clock -- some species take as little as 12 weeks to mature -- allowing them to retain the physical characteristics of baby dinosaurs.

The results of the study appeared May 27 in an online edition of the journal Nature.

"What is interesting about this research is the way it illustrates evolution as a developmental phenomenon," said Arkhat Abzhanov, associate professor at Harvard and study co-author. "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." While it's clear simply from looking at the skulls of dinosaurs and modern birds that the two creatures are vastly different -- dinosaurs have distinctively long snouts and mouths bristling with teeth, while birds have proportionally larger eyes and brains -- it was the realization that skulls of modern birds and juvenile dinosaurs show a surprising degree of similarity that sparked the study.