Evolution of lungs
Lungs are crucial for life on land – they allow breathing in dry conditions, delivering oxygen and expelling carbon dioxide. Their appearance in the history of life on Earth was a significant, one-time revolution, which founded the success of amphibians, reptilians, birds, and mammals. How did it happen?
To better understand the evolution of lungs, we have to look at the evolution of the first vertebrates, which lived about 500 million years ago.
The oldest evidence of lung development is found in the reptile Edaphosaurus, from the Triassic, around 250 million years ago. These reptiles had lungs and tracheae (tubes that carry air) but no larynx (voice box). This meant they had to develop a mechanism to produce sound. This could be done by the expansion of air sacs in the lungs, or the formation of the larynx itself. The development of the larynx was eventually seen in the tetrapods (four-legged vertebrates), which first appeared in the late Triassic (around 200 million years ago).
The modern larynx is an organ found in all vertebrates that has the function of producing sounds.
The earliest evidence of the larynx in birds is a well-preserved fossil of a Jurassic bird called Megapnosaurus. This shows the presence of a soft tissue larynx. However, the existence of a modern larynx in birds is disputed. Some experts believe that it evolved from a branch of the trachea, the tube that carries air in the lungs. Others suggest that the larynx is a separate organ.
The earliest fossil evidence of the larynx in mammals is from an early mammal called Molnarohyus. It shows a small organ called the hyoid bone, which is a bone in the neck. The hyoid bone is an important part of the respiratory system. It supports the larynx and allows it to move up and down. The larynx is a muscular tube, which is supported by the hyoid bone.
In a living mammal, the larynx can be seen in the voice box, which is a muscle in the neck that acts as a sort of windpipe. It allows air to pass through the lungs into the lungs, and then into the mouth and out of the mouth.
How did lungs evolve?
The evolution of the larynx was important, because it enabled mammals to make sound. The lungs were a completely new organ that evolved in the early evolutionary history of the first mammals. The lungs are an essential part of the respiratory system, but are not the same as the larynx. The larynx is a muscular tube that moves up and down in the neck, and is the site of sound production.
The development of the larynx in early mammals was a one-time event. The lungs were also developed, but as part of a different process. This was a unique development, and not seen in any other animal. The development of the lungs and the larynx are linked, and are not the same.
The lungs evolved as a means to extract oxygen from the air, while the larynx developed as a way to produce sound. This led to the development of the larynx. This is why the larynx is found in all vertebrates, and the lungs are not.
What are the next steps in the evolution of lungs?
Lungs in early tetrapods
In the late Triassic, the first tetrapods, which are four-legged animals, evolved. The first tetrapods, such as Triceratops, were amphibious, and spent much of their time in water. They were not the first animals to have lungs, but they did have lungs, and they evolved to develop the ability to breathe air.
The first tetrapods had to make a transition from water to land. The lungs of these early tetrapods developed to enable them to breathe air. They evolved into air sacs in the lungs, which provided a reservoir of air for the animal to breathe.
The first air sacs were made up of the rib cage, which expanded and filled with air. These air sacs were filled with air by the breathing muscles of the rib cage. The air sacs were like tiny air pockets, which were sealed off by cartilage, which is a tissue that connects the rib cage to the lungs.
The air sacs were filled with air by the breathing muscles of the rib cage.
This mechanism of air sac formation was a precursor to the modern lung. Air sacs in the lungs are important because they are used to fill the space between the alveoli (tiny air sacs in the lungs). The air sacs allow the lungs to expand, and can expand to fill the space between the alveoli. This is the way that the lungs expand and fill with air when we breathe.
When air is inhaled, the muscles of the rib cage squeeze the air sacs, and the lungs expand to fill the space between the alveoli. When we breathe out, the muscles relax, and the lungs contract to return to their normal size.