Dinosaurs Breathed Just Like Birds

Only few doubt that birds are just living dinosaurs. Besides clues like feathers and similar bones, a new research comes with novel proofs that dinosaurs did resemble birds.

The researchers at the University of Manchester point in their article published in the Proceedings of the Royal Society B: Biological Sciences that dinosaurs breathed just like birds. Fossil bones of theropod dinosaurs, like the Velociraptor, from which birds evolved, revealed similar breathing systems to modern diving birds, like sea birds and wildfowl and it is the first time when the subject of dinosaur respiration has been tackled.

"A number of studies have shown that dinosaurs were the direct ancestors of birds and have identified a suite of avian characteristics in theropods. Our findings support this view and show that the similarities also extend to breathing structures and that these dinosaurs possessed everything they needed to breathe using an avian-like air-sac respiratory system," said lead researcher Dr Jonathan Codd, of the Faculty of Life Sciences.

Birds have a complex and extremely effective respiratory system, with air sacs expanding from their lungs, a fact that makes the oxygen supply pass twice through the lungs during one breath, delivering the increased oxygen requirements necessary for providing high energy amounts for flight.

The team compared fossilized bones of maniraptoran dinosaurs and ancient birds like Archaeopteryx, discovering unique breathing structures, called uncinate processes (bony projections of the ribs that stiffen the thoracic box), also in the dinosaurs.

"Our work on modern birds has shown that the way these animals breathe is more complex than originally thought. The uncinate processes are small bones that act as levers to move the ribs and sternum during breathing. Interestingly, these structures are different lengths in different birds - they are shortest in running birds, intermediate in flying birds and longest in diving birds. The dinosaurs we studied from the fossil record had long uncinate processes similar in structure to those of diving birds. This suggests both dinosaurs and diving birds need longer lever arms to help them breathe." said Codd.

"Finding these structures in modern birds and their extinct dinosaur ancestors suggests that these running dinosaurs had an efficient respiratory system and supports the theory that they were highly active animals that could run relatively quickly when pursuing their prey." he explained.