As early as 1997, a computer simulation of Microsoft at the time Chief Technology Officer Nathan Melward showed that the huge tail of the dinosaur under the sauropod can crack like a bullwhip, breaking the sound barrier, and producing sonic boom , thus making headlines. Paleontologists think this is an interesting possibility, although some people doubt it. Now a new team of scientists has solved the problem and built their own Apalong tail simulation model. The maximum possible speed in the new simulation is 10 times slower than the speed of sound in standard air.
2020s was still at Microsoft, Melward, who had long loved dinosaurs, accidentally discovered a book by zoologist Robert McNeill Alexander, which speculated whether the tails of some sauropod dinosaurs were used to make huge noises like bullwhips as defense strategies, mating summons or other purposes. This structure is a bit like a bullwhip, because every continuous vertebrae on the tail is about 6% smaller than its predecessor. The physics community already knows that the whip rupture is a shock wave or sonic boom generated by the speed at which the fine tip breaks through the sound barrier.
Melward wanted to put this speculative suggestion into practice and contacted paleontologist Curry by email. The two analyzed the fossils, developed computer models, and performed several computer simulations to test the biomechanics of the sauropod dinosaur tail. They also compared these simulations to the mechanics of the whip.
They concluded that the tail swing left and right can emit an energy wave, accelerating along the length of appendage , thereby obtaining momentum, so that the end of the tail reaches a speed of more than 750 miles per hour. The speed of sound varies according to the medium and ambient conditions, but in air at 0°C, the speed of sound is usually 740 mph. Melward and Curry pointed out in their paper that only the last two to three inches of the tail can reach supersonic . They also believe that the farthest part of the tail may extend through a piece of skin, tendon or keratin to the last vertebrae, similar to the tip of a whip made from cow or kangaroo skin, which are strong enough to withstand supersonic speeds.
Melward presented his latest research at a meeting in 2002, reporting that the maximum potential speed is 1300 mph, which will produce a sonic boom of about 200 decibels. Other evidence includes: Some sauropod fossil specimens fuse vertebrae in a critical transition zone between the hard bottom and the flexible part of the tail, just as bullwhip eventually fails at the junction between the thick shank and the flexible leather part.
Paleontologist Kenneth Carbent is one of the most outspoken skeptics of the sonic boom hypothesis. In 1995, he told the New York Times : "Frankly speaking, computer simulation is another example of garbage entering and leaving garbage." It took nearly 20 years, but Melward presented such a model at the 2015 Vertebrate Paleozoic Society Conference.
This model is made of aluminum, stainless steel, neoprene and Teflon and is 12 feet long (3.6 meters) long, about a quarter of the tail of a sauropod dinosaur. The 82 bones on the tail all contained the correct joint angle, and Melward placed weights on each vertebrae to simulate the weight of the flesh. Finally there is a "popper": a little processed leather that simulates the tip of a bullwhip. The model is attached to a camera tripod, representing "Dinosaur Butt". Melward and others then conducted a series of tests, pulling the tripod handle, causing the model's tail to swing, creating sharp "cracks" like bullwhip. They shot all the tests on high-speed video to ensure accurate measurements. The tail of the
model reached 360 meters per second, about 805 mph. Carpenter was impressed, but still doubted, noting that the scale model lacked a connection structure from one vertebra to the next, which would limit left and right movements, and the skin and muscle layers were also limited. As for poppy, Carpenter told Live Science that breaking its tail at supersonic speeds could cause skin rupture or bleeding at the tip, ultimately leading to inflexible scar tissue."It's hard for me to imagine evolution taking the sauropod dinosaur's tail on a road where it can only be used a few times and then it's worthless," he said.
This gives us the latest article. Simone Conte of the NOVA School of Science and Technology in Portugal, together with several colleagues, began to adopt more multifaceted methods to improve early computer simulations. They combined state-of-the-art multibody models with soft tissue stress resistance simulations to test the biomechanical properties of the apalon tail.
Their model tails are over 30 feet (12 meters) long and weigh 3187 pounds (1446 kg). It has 82 cylinders representing the vertebrae attached to the fixed hip bone base. These cylinders move in arc shapes, causing the tail to move in a whip shape. Their model tails have a maximum speed of only 33 meters per second, or below 74 miles per hour, which is too slow to produce a sonic boom, suggesting that the tails of sauropods are much harder than previously thought.
Also, when they place the model tail at supersonic speed, the tail inevitably breaks and cannot withstand stress. Conte et al also tried to add structures that simulated the tip of the bullwhip in their simulations: one consisted of three segments of skin and keratin, one consisted of woven keratin filaments and the other consisted of soft tissue. None of these can withstand the pressure of supersonic speed. "The evidence obtained from computer simulations and estimation of soft tissue stress tolerance does not support the hypothesis of sauropod supersonic tails." Due to the effect of joints and air resistance with the sacrum, the limits at the bottom of the tail reduce the maximum speed that can be achieved. Soft tissue thrusters cannot withstand the high stresses applied by the movement of sound because increased mass can cause tail failure or increased air resistance can further reduce tail speed.
