Dino whiplash.

Did huge lumbering dinosaurs move faster than the speed of sound? That may be a tall tale. But some paleontologists (dino scientists) think their lashing tails may have sped faster than modem-day jet planes.

While studying fossils of long-necked dinos, some paleontologists noticed that dino tails resembled whips. Starting with a thick base, an Apatosaurus' 12.5-meter (41-ft) tail tapered into a thin tip.

Try to picture the Apatosaurus (above right) lashing its tail, much like a dog wagging its own tail. The difference is that the dino's tail was much longer, stronger, and more muscular. An instant flick of the dino's tail probably generated a lot of energy at its base. The force swiftly built up as it traveled down the tail's entire length. By the time the energy reached the tail tip, that dino "whip" cracked faster than 1,200 km (760 mi) per hour--the speed of sound.

Just as the tip of a whip produces a cracking sound when it travels faster than sound, a dino's 1,590-kg (3,500-lb) tail would have thundered, producing a supersonic boom.

To test this sound theory, paleontologist Philip Currie of the Royal Tyrrell Museum in Alberta, Canada, and computer scientist Nathan Myhrvold (right) of the Microsoft Corporation created computer simulations of dino tails, The simulations would tell them if it was possible for a dino tail to travel faster than sound. The result? It was easy- to find simulations that produced supersonic motion, Currie and Myhrvold say.

Other scientists remain skeptical. Paleontologist Kenneth Carpenter of the Denver Museum of Natural History says for a dino to produce a super sonic boom, it would have to whip its tail so I hard the pain might have flattened the dino. Plus, such force could easily cause tail damage, even I break off the tip.

That may be true, respond Currie and Myhrvold. But if the dino tail-tip was just skin or tendon extending past the last vertebra (or bone), the damage would have been a mere dino-sore. Also, dinos probably didn't crack their tails a lot. They may have rattled them once in a while to play top gun over other dinos, scare off rivals, or even attract mates. That's one mean tail.