Though some scientists have proposed that predatory dinosaurs had lungs similar to crocodiles and other reptiles, a new study published in this week's issue of the journal Nature suggests the ancient beasts boasted a much bigger, more complex system of air sacs similar to that in today's birds. The finding is one of several studies in recent years to paint a new, more avian-like portrait of meat-eaters such as T. rex: The creatures may have had feathers, incubated their eggs, grown quickly and perhaps even breathed like birds.
"What was once formally considered unique to birds was present in some form in the ancestors of birds," said Patrick O'Connor, an assistant professor of biomedical sciences at Ohio University's College of Osteopathic Medicine and lead author on the study, which was funded in part by the National Science Foundation.
O'Connor and collaborator Leon Claessens of Harvard University visited museums in New York, Berkeley, Chicago, Pittsburgh, Washington, D.C., Berlin and London to examine the bones of ancient beasts, and also studied a 67-million-year-old dinosaur, Majungatholus atopus, that O'Connor had discovered in Madagascar as a graduate student in 1996. They compared the dinosaur skeletons with those of modern birds to draw comparisons of how the soft tissues in the dinosaurs may have been structured.
Birds long have fascinated biologists because of their unusual pulmonary system. Pulmonary air sacs prompt air to pass through the lungs twice during ventilation. This system also creates holes in the skeleton of birds, which has led to a popular notion that birds have "air in their bones," O'Connor said.
The new study, which examined how the air syst