The origin of birds and their evolution has been one of the greatest mysteries of paleontologists and biologists. Do you want to learn what we know at the time of writing?
There is some consensus: most scientists believe that birds evolved from dinosaurs. More specifically, it is believed that they came from coelurosaurs – a family of dinosaurs that include species such as the famous velociraptor.
As far as we know, the link between birds and dinosaurs is pterodactylene, or archaopteryx, which was like a cross between the birds we see today and dinosaurs with feathers. It had large feathers, sharp teeth and could fly.
The study of the origin of birds began around Darwin’s time. One year after he published On the Origin of Species , scientists discovered the first fossilized feather. It was the starting point for a number of different theories and potential connections within the evolution of birds.
A great similarity between birds and dinosaurs is their feathers. Although many had simple, fur-like feathers, there were also dinosaurs with feathers almost as complex as birds.
But there is an even greater similarity: their bone structure. There are clear parallels in their skeletons, especially in the fork bone and sternum, both of which are very important for birds.
The dinosaurs’ lungs also had similar air sacs to those we see in birds. Some researchers believe that dinosaurs even slept in a way similar to birds, by placing their head under their limbs to keep it warm.
The biology and behavior of dinosaurs also give us clues to the origin of birds. Both have (and had) a calcium-rich cavity in their bones, which today helps birds produce the shells for their eggs.
Many fossilized dinosaurs have been found hatching their eggs. The fact that dinosaurs had no teeth suggests that their parents pushed their food towards them. Researchers have also found small stones in the digestive systems of dinosaurs. These helped them digest the food, just like the muscle stomachs of birds.
But if the birds originated with the dinosaurs, how did they develop to be able to fly? It is important to remember that pterodactyls were not dinosaurs. This has led to two theories: either fast-running dinosaurs began using wings as a way to keep their balance, or tree-dwelling dinosaurs used them to fall more safely.
This would mean that the wings did not start as a tool to fly. Slowly but surely, their “arms” developed to help them balance or fall more slowly. Then they went on to glide, and eventually it led to their descendants (the birds) being able to fly.
When the dinosaurs became extinct, some of them survived. Their descendants then made the development of birds possible, and in today’s world there are now millions of them in the world. Isn’t that amazing?