From time to time scientists start a study to test some of them strange and crazy Hypothesis that makes you wonder why. But let’s give in to them; it can be fun.
A new study by a team of paleontologists and aerospace engineers has a dinosaur‘s tail thrashing about to see if long-necked sauropods could whip their limbs faster than the speed of sound – fast enough to create the crackling of a small sonic boom.
previous research has suggested that the dinos could if their tails had a bullwhip-like structure that increased length. If that were true, these herbivores dinosaur might have used their tails to defend themselves against predators or nosy neighbors.
But other paleontologists weren’t so sure.
Many theories have been circulated as to why diplodocid Dinosaurs, a group of sauropods that includes brontosaurus, have such long, slender tails.
They could be a defensive weapon, sure. But diplodocids may have used their tails to make noise, to balance their long necks, to kick the ground around them, or as a “third leg” to steady them like a rearing kangaroo.
Among the diplodocid family are some of the longest creatures that have ever walked the earth, so it’s no wonder their body forms are a curiosity to engineers and paleontologists alike.
No full diplodocid tail has been found so far, so the researchers behind this latest study, led by paleontologist Simone Conti of NOVA University near Lisbon, Portugal, pieced together what was known from five fossilized diplodocid dinosaurs.
They added material properties of soft tissues like skin, tendons and ligaments to their models – in addition to modeling the 80 or so vertebrae (bones) that diplodocids have in their tail alone. Humans, by comparison, only have 33 from crown to tailbone.
The morphology of the inner soft tissue of sauropod tails has remained a great unknown ever since skin marks and Bone are preserved in the fossil record.
So Conti and colleagues concluded the tail’s soft-tissue composition based on bone structure. They also estimated skin thickness based on crocodile skin and modeled the mechanical stress these soft tissues could withstand when the tail whipped back and forth.
In the computer models, the stout appendage attached to an immobile hip bone base weighed 1,446 kilograms (3,187 pounds) and was 12 meters (40 feet) long.
It sounds strong – but only up to a point. The skin is a complex organ laced with collagen fibers that give it elasticity, but become “almost completely brittle” under high stress, according to Conti and colleagues explain in her paper.
They simulate the mechanical properties of soft tissue and the rotational movement of the tail found diplodocidal tails were “stiffer than previously thought, with the tendons and musculature playing an important role in avoiding disarticulation of the vertebrae once the tail begins to move.”
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But the simulated tail didn’t break the sound barrier due to friction of the tail muscles and vertebrae and drag. And if it did, it would be cracked.
At its tip, the tail was moving at speeds of about 30 meters per second, or 100 kilometers per hour, ten times slower than the speed of sound (340 meters per second) and not fast enough to produce a sonic boom.
A thin, whip-like tail could not withstand the stress of the speed of sound without the tail breaking, whether made of braided keratin filaments or not other dinosaur taxathree segments of skin and keratin, or a fleshy, flail-like mass.
“Even if the hip greatly increased the motion of the tail, our estimate of soft-tissue drag would not support the supersonic motion of dinosaur tails,” Conti and his colleagues say write.
However, as the researchers point out, this does not rule out the possibility that diplodocids could have used their tails to land defensive strikes or engage in intraspecific fights.
Conti and co. calculated the impact force of the tip of the tail, moving at a speed of about 30 meters per second, and found that it would equal the pressure exerted by a golf ball traveling at 315 kilometers (196 miles) moved per hour.
Sonic boom or not, it must hurt.
“Such pressure would not be able to break bones or injure skin, but would deliver a reasonable punch,” says Conti and his colleagues write.
The study was published in Scientific Reports.
