Some scientists believe the Apatosaurus may have moved its 45-foot (14-meter-) long tail like a bullwhip, with its 6-foot-(1.8-meter-) long, skinny tip creating a loud crack. Recent computer models have compared the movement of a model Apatosaurus tail with the motion of a bullwhip. These studies show it is not only feasible, but the relatively slow motion at the base of the tail would translate into supersonic speeds at the tip. This would have created a loud sonic boom of about 200 decibels—much louder than the 140 decibels of a jet taking off.

In the past, paleontologists thought the tail of sauropods like Apatosaurus were mainly used for balance, or to swat rivals. But the tip of the tail contained tiny, fragile bones that could have easily broken in a fight. Now, some scientists think the loud crack from the tail tip could have been used to scare away predators, establish dominance in a herd, resolve disputes, and even to attract a mate.