Physical model to show how dinosaurs may have whipped their tails in supersonic speed


Imagine a tail tip of a giant Sauropod dinosaur (pictured above) cracking at the speed of sound. Obviously, this deft natural action has not been seen (or heard) for at least 66 million years. But that is about to change with an actual physical model contrived in the lab. At least that is what computer scientist Nathan Myhrvold aims to recreate, as he aptly puts forth his notion on how dinosaurs might have been among first living creatures who could move (some part of their bodies) beyond the speed of sound.

The ‘giant’ in question here pertains to Sauropod dinosaurs, an infraorder of saurischian dinosaurs, known for their long necks, long tails and four humongous, pillar-like legs. In fact, the most striking nature of such herbivorous Sauropod dinosaurs related to their massive sizes, thus making their group among the largest animals to have ever lived on land. However, in contrast to their bulky physical form, the tails of some of these specimens (like the Apatosaurus) tended to taper to an extended whip-like bearing. This tapering form equated with unique cylindrical shaped bones conforming to the ‘whip’ portion.


Now, the idea of these dinosaurs cracking the tip of their tails, was first put forward in 1989, by McNeill Alexander of the University of Leeds, UK. According to him, the male Sauropod dinosaur used this action to attract the attention of the females. And it was this very conjecture that impressed the dinosaur enthusiast inside Myhrvold. As a result, during his tenure as the head of research at Microsoft, the scientist (who is currently the CEO of Intellectual Ventures) created a virtual computer model of the Apatosaurus tail in 1997. On incorporating physics, he found that a certain movement produced by the tail base could have generated a wave that accelerated further down the tapering-end. This acceleration in turn could have reached a supersonic speed, with the tail snapping at its end like the bullwhip of Indiana Jones.

To justify this series of intricate motions, Myhrvold has designed a real-time 3D model of a complete Apatosaurus fossil with all the ‘bells-and-whistles’, including the tiny vertebrae that account for 82 pieces. He made a slew of other adjustments, including the incorporation of neoprene bumpers that would replicate the intervertebral discs and the addition of weights to the vertebrae that would mimic the flesh on the tail. The resultant mega-model is over 3.5 m (11.5 ft) long, but is still insubstantial to the massive 14-m long tails originally exhibited by the Apatosaurus. This replica fossil was then installed on a tripod and finally supported by counterweights . As for the motional attribute, it can be activated by rowing a rod-handle back and forth – which generates the rippled effect, leading to the supersonic ‘crack’ at the end.


3D model of the dinosaur tail, Credit: Duncan Smith/Intellectual Ventures

However, some palaeontologists are not convinced by this hypothesis of dinosaur tails reaching supersonic speeds. For example, Ken Carpenter, who is currently the director of the Utah State University Eastern Prehistoric Museum, put forth his conjecture on how the cracking action can disturb the living tissue, thus leading to scabs that could further constrain the motion of the tail-end. Moreover, according to the expert, one should also take into consideration the skin texture of the tail that could have prevented such a speedy motion.

On the other hand, Myhrvold holds his own, by explaining how such a skin piece wouldn’t matter until the very end of the tail comes into action. For example, if we examine a bullwhip, we can see a piece of string attached at its end that gets worn down over time, and is eventually replaced. Now, according to Myhrvold, in dinosaurs, this piece probably comprised a dead skin that would initially grow and then fall off (like our nails).

In any case, it is currently very difficult to verify either of the hypotheses – primarily because we have still not been able to find any fossilized remains of such a tail tip. However, many of the confusing predicaments might be solved if researchers manage to discover skin impressions from the end portion of such tails.


Size comparison of a Sauropod dinosaur and an average human.

Source: NewScientist

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