Dinosaur fossils with suspiciously curved arms at the elbow and wrist may hint at the presence of a missing tendon that underlies all modern bird flight. If the researchers at the University of Tokyo are right, this pose could provide clues to the path that surface dwellers took to take to the skies. The evolution of wings—powerful enough to lift off the ground—is one of the great mysteries of paleontology. It not only excites the minds of scientists, but also opens up interesting prospects in the event that answers to the questions posed are received.
The very first birds
Pterosaurs are famous for being the earliest known finds to have actually flown nearly 200 million years ago. However, these massive ancient reptiles weren’t dinosaurs, leaving the direct ancestors of birds to figure things out on their own when it comes to flight.
Bird dinosaurs evolved much later from bipedal feathered theropods. after 80 million years or more after pterosaurs have already learned to fly. Despite these vastly different origin stories, birds use a strikingly pterosaur-like structure to stay aloft, which, like feathers, seems to have evolved long before flight itself.
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What helps a bird to fly
Propatagium is a membrane, present in all living things that flap their wings today, including birds and bats. Some gliding mammals even have a similar structure on their parachute-like upper limbs.
The best way to present propatagium Extend your arm out to the side with your elbow and wrist bent. Now imagine a tendon stretching from your shoulder to your arm, forming the bridge or “leading edge” of the wing. This “bridge” allows flying birds to flex and extend the wrist and elbow simultaneously during the flapping motion. The structure essentially imparts lift to bird flight, allowing the animal to control two joints at the same time.
For pterosaurs, its role is less clear, but the propatagium apparently controlled takeoff and landingchanging the flow of air over the upper surface of the wing.
Ученые показали, как выглядел мозг самого крупного хищного динозавра.
Without which birds could not fly
Some scientists believe that without the presence of a special tendon, birds, bats and dinosaurs would never have left the ground. There are many other factors, including the shape and composition of the body, but it is the presence of a special joint that is the last factor without which flight would not be possible. This like the wheels of the most perfect machine She won’t go without them.
Propatagium is not found in flightless birds, which is one of the reasons why scientists have decided that it is necessary for flight. This is stated by paleontologist Tatsuya Hirasawa from the University of Tokyo. He argues that in order to understand how flight developed in birds, we must understand how the propatagium developed.
The problem is that propatagium is a soft tissue, meaning that it is rarely preserved in the fossil record. Moreover, this tendon is so thin that it does not leave noticeable marks on the bones to which it is attached. Luckily, Hirasawa and his colleague Yurika Uno found a way to “see” the tendon even when it’s gone. The key is to know how the propatagium restricts the animal’s movements.
For example, when a modern bird dies, this membrane naturally holds the animal’s wrist and elbow in a flexed position.
Comparing the prominent elbow angle to the curve of the arms in non-avian theropod fossils, the researchers found evidence that a propatagium-like structure likely extended across the shoulder and wrist of several land-dwelling dinosaurs.
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What do birds and dinosaurs have in common?
For example, the limb angles seen in the fossils of many “maniraptors” (including velociraptors) were slightly larger than those of modern birds, but they still hinted at the presence of some early structure similar to the propatagium.
To support these predictions, the researchers also identified soft tissue remains of what may be the early propatagium of two maniraptor fossils: a turkey-sized caudipteryx and a four-winged microraptor.
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Understanding how birds learned to fly, will allow not only to understand the history of the evolution of species, but also many other things. For example, how living beings migrated, what changes lead to others, what mechanisms are responsible for movements, and that’s not all. Understanding these things has more than once led to the creation of mechanisms that we use every day. Now another contribution has been made to the treasury of inventors.