Paleobiologists from the University of Manchester (United Kingdom) and the University of Louisiana (USA) compiled 3D models of the chest and light dinosaurs of the Mesozoic and modern birds.
It turned out that many elements of the respiratory system of birds appeared in ancient lizards. To such a feature, scientists pointed out the similarity of the structure of their rib-vertebral joints and chest, forming a strong "frame" that "supported" the lungs. The lungs themselves were rigid, which means they did not expand during inhalation and did not shrink during expiration, like in mammals. The air passed through them "through", with about 75% of the oxygen turned out to be in special air bags, similar to those of birds.
Light giant predators literally washed with oxygen, so that animals could develop great speed in pursuit of prey. So, the velociraptor was able to accelerate to 64 km / h.
“We came to the conclusion that dinosaurs had the same effective respiratory system as birds. This explains why dinosaurs dominated and flourished in the Mesozoic era, when the oxygen content in the atmosphere was only 10-15% compared with the current 20%, ”said study author Robert Brocklhurst.
Recent paleontological discoveries indicate other similar features of dinosaurs and birds, for example, the tail, covered with feathers.