RESPIRATORY SYSTEM AND AIR SACS
A comparison of the air sacs of dinosaurs and birds
Meat-eating dinosaurs such as the velociraptor have been discovered to have had breathing structures called uncinate processes that are also present in modern-day birds. Uncinate processes are small bones that act as levers to move the ribs and sternum during respiration. Meat-eating theropods had long uncinate processes similar to those in diving birds like pelicans.
In Argentina, a dinosaur estimated to be 85 million years old was discovered to have a system of air sacs (bellows) to help pump air through its lungs. This, interestingly enough, is the same way birds breathe. These air sacs often invade the bone creating pockets of air and a porous texture called pneumatization. This bird-like breathing system may have evolved to keep unbalanced, two-legged theropods on their feet when in motion, or they may have been part of a cooling mechanism. This system is also much more efficient that its reptilian and even mammalian counterparts. With new developments in geochemical data of the time, we’ve discovered that the atmospheric oxygen concentration at the time was only about half of what it is today. These air sacs may have given the dinosaurs the evolutionary advantages they needed to out-compete the mammals and survive the mass extinction.
In Argentina, a dinosaur estimated to be 85 million years old was discovered to have a system of air sacs (bellows) to help pump air through its lungs. This, interestingly enough, is the same way birds breathe. These air sacs often invade the bone creating pockets of air and a porous texture called pneumatization. This bird-like breathing system may have evolved to keep unbalanced, two-legged theropods on their feet when in motion, or they may have been part of a cooling mechanism. This system is also much more efficient that its reptilian and even mammalian counterparts. With new developments in geochemical data of the time, we’ve discovered that the atmospheric oxygen concentration at the time was only about half of what it is today. These air sacs may have given the dinosaurs the evolutionary advantages they needed to out-compete the mammals and survive the mass extinction.