A computer model suggests that Archeopteryx may have used two or three powerful jumps to build up enough speed to fly.
Bird flight in its modern form did not appear all at once. Early feathered animals still had dinosaur traits, so the ability to take to the air likely evolved in stages.
Archeopteryx It lived about 150 million years ago and has long been central to this issue. A computer model now suggests that it could build up enough speed to fly in just two or three powerful jumps.
Ancient birds retained dinosaur features
Archeopteryx He had wings and flew feathersBut also a long bony tail, clawed fingers and teeth in the jaws without a beak.
This combination helps explain why understanding the transition from dinosaurs to birds is important.
“Archeopteryx “It is the first true bird,” said Dr. Neil Gostling, a paleozoologist at the University of California. University of Southampton. “It was covered in feathers and had wings, but it also retained a number of distinctive dinosaur features, such as a long bony tail, claws on separate fingers, and teeth in a beakless jaw.
“It was not a particularly advanced ‘bird’ compared to the ones we know today.”
The wings alone were not enough
Modern birds often push forcefully with both legs while initiating powerful wing beats. Archeopteryx He lacked a everted sternum Breast bone A ridge stabilized the large flight muscles, and shoulder movement was limited.
“We know Archeopteryx Professor Marcus Heller, a researcher at the University of Southampton, said: ‘It couldn’t rely on its wings to take off – with no arched breastbone, and a shoulder that couldn’t lift the wing above its back – so we asked what its legs could contribute.’
“It turns out that this is where takeoff is achieved: the legs generate the force, and the wings then take over.”
Her hind legs offered another path. The reconstructed hind legs made up about 13% of its body mass, compared to about 9 to 10% in living birds.
Reconstructing the take-off of ancient birds
The team built a biomechanical model, which is a computer simulation of the body’s movement and force.
It represented an animal weighing about 14 ounces (400 grams), near the middle of published estimates ranging from 7.1 ounces (200 grams) to 1.3 pounds (600 grams).
The researchers used measurements from Zebra finch Take-off, including body movements and the force of each push to the ground. Moving X-ray images tracked the birds’ joints, and the team adjusted those movements to suit them Archeopteryx Leg proportions.
The model represents 32 muscles and their associated tendons, with force estimates derived from magpies, guinea fowl, and Nile crocodiles.
It compared the torsional force required at the hip, knee and ankle with the estimated force those muscles could produce.
The team tested a single jump, repeated jumps, and jumps combined with a small downward stroke of the wing. The two-legged jump uses both hind legs, and the model attributes all initial speed to them.
Powerful jumps made the flight possible
A leg-assisted jump produced a typical speed of 6.7 mph (2.98 m/s). The impulse lasted from 66 to 74 ms, with the ankle muscles imposing the main limit.
That was less than the estimated speed of 15.7 miles per hour (seven meters per second) needed to continue the journey. After three jumps, the animal reached a speed of 14.9 miles per hour (6.66 meters per second), after which its wingbeats could reach the target speed within 0.23 seconds.
With downward Wing In a stroke between two jumps, the model reached 14.0 mph (6.24 meters per second). Continuous flutter can reach the target speed within 0.36 seconds.
“Our findings show that a medium size, 400 grams Archeopteryx “It could have achieved a sustained flight speed of seven meters per second with three bipedal hops, or two bipedal hops with a downward flutter between jumps,” said Dr. Eric Melak, a former doctoral researcher at the University of Southampton.
Modern birds still use hops
“All birds push with their legs when they take off,” Dr. Gostling said. “In fact, up to 90 percent of the force required to get off the ground comes from the legs, and then the wings take over.”
“Archeopteryx He would take off either with a hop, then a hop, then a hop and then a lot of fluttering, or a hop, a flutter, another hop and a lot of fluttering.
Many modern birds, including crows, magpies and seagulls, can take off with a single jump but also use multiple jumps to get into the air.
They tend to rely on one powerful jump when they feel frightened, stressed, or threatened, while using two or more jumps when launching into less urgent circumstances.
Many details of the flight remain unconfirmed
The model shows that multiple jumps were physically possible, not that the fossil record proves that this behavior occurred. The results are based on estimates of the posture, muscle strength, wing force, and speed maintained after landing.
Zebra finches are more than 10 times lighter than a typical model Archeopteryx. Comparison with carrion crows showed a similar reliance on legs, but modern birds are still not a perfect match for a Jurassic animal.
The muscle model used estimates of maximum force rather than taking into account every feature of living tissue, including muscle fiber height and length tendon Stretching. Archeopteryx Maybe he needed to get closer to those limits, especially at the ankle.
Changing the body’s balance point and the location where the foot presses into the ground changed the speed of a single jump from 5.8 to 7.0 mph (2.58 to 3.12 meters per second).
Flight path calculations also assumed a launch angle of 45 degrees, little air resistance, and maintaining forward speed between jumps, so exact values remain uncertain.
Frequent jumps may explain the flight
The results support a ground-based flight path, in which the legs generate speed before limited wingbeats take over. They do not rule out climbing, gliding, or other launching behaviors.
However, the frequent jumps provide a possible transitional stage between galloping dinosaurs and modern birds. This strategy would have reduced the need for the explosive single jump used by many birds today.
Archeopteryx He may not have been able to achieve flight in a single jump, but a short series of jumps could have given his wings enough speed to function.
The study is published in the journal Developmental biology.
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