A letter from Harvard University to Nature reports that birds have paedomorphic dinosaur skulls. What this means is that birds could be dinosaurs that never matured. The Los Angeles Times reports,

Evolutionary biologist Arkhat Abzhanov of Harvard University noted an apparent resemblance between the skulls of juvenile dinosaurs and adult birds and decided to do a more comprehensive study. With graduate student Bhart-Anjan Bhullar, he used CT scanners to examine dozens of skulls, including modern birds, theropods -- the dinosaurs most closely related to birds -- and earlier dinosaur species. By identifying various landmarks on the skulls, they were able to track how the skull shapes had changed over the years.

The Harvard biologists found that the changes during evolution were from paedomorphosis. Paedomorphosis is retention by an organism of juvenile or even larval traits into later life. In terms of evolutionary theory, the process of paedomorphosis suggests that larval stages and developmental phases of existing organisms may give rise, under certain circumstances, to wholly new organisms.1

To read the full Los Angeles Times article, click here http://www.latimes.com/news/science/sciencenow/la-sci-sn-birds-dinosaurs-20120529,0,7306734.story?track=rss.

1paedomorphosis. (2012). In Encyclopædia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/438082/paedomorphosis