A prehistoric armadillo-like animal swung its tail like a baseball bat, taking advantage of the “sweet spot” the same way tennis and baseball players do today, according to a study published in the journal Proceedings of the Royal Society B.
The tail sported spikes at a specific location that allowed the mammals, known as glyptodonts, to deliver a strong blow while minimizing the risk of harming the tail, the researchers found; spiny-tailed dinosaurs may have used the same mechanism. Known as the “sweet spot” today in sports like baseball, this so-called “center of percussion” helps athletes avoid wrist injuries. “The center of percussion is a point where you can deliver a very powerful blow with a baseball bat, a tennis racket, a sword, an axe or any hand-held implement, but the forces against your hands are almost zero” [Discovery News], said lead author Rudemar Ernesto Blanco. The glyptodont, which went extinct about 8,000 years ago after its emergence about 2.5 million years ago, would have swung its tail about 15 meters per second–about as fast as a modern-day tennis player swinging his or her racket.
To evaluate the center of percussion on the tails of glyptodonts, researchers determined that in many glyptodont species … rings of bony scutes, or plates, on the tails were fused, turning the animal’s tail into something akin to a baseball bat. Measurements and calculations found that each tail’s sweet spot landed right where scientists had previously speculated the biggest spikes once existed: at the center end of the tail [Discovery News]. This suggests that the animals’ tails were used for inflicting the maximal damage when fighting off predators. The findings also imply that evolution helped the tail develop into an effective fighting tool. Says John Hutchinson, an expert on dinosaur biomechanics: “[The center of percussion] is what evolution should produce, of course, but it’s always satisfying finding different kinds of evidence for sufficiently good biological design” [Discovery News].
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Image: Rudemar Ernesto Blanco
August 27th, 2009 at 12:04 pm
It seems to me that the “without hurting the wrists” idea is a little off base. If one hits outside the sweet spot, the rotation might marginally threaten the lower side thumb (left hand for right handed batters, etc); but the angle wouldn’t hurt the wrist. The main virtue of the sweet spot is the transfer of all the instantaneous angular momentum of the bat to the ball. If there were such a threat to wrists, the playing time of players would be measured in weeks.