Could a dinosaur tail go supersonic?

The dinosaur formerly known as Brontosaurus could certainly do a lot of damage with its long tail — but just how fast could that tail whip?

Years ago, a team of researchers — including Nathan Myhrvold, a former Microsoft executive who’s now the CEO of Bellevue, Wash.-based Intellectual Ventures — built a quarter-scale dinosaur tail from 3-D printed vertebrae and a bullwhip popper, and thrashed it around. Their aim was to show that the diplodocid dinosaur now known as Apatosaurus louisae could whip its tail with a supersonic crack more than 150 million years ago.

The team determined that the tail could indeed go supersonic, producing a crack as loud as the report of a naval gun and most likely scaring off potential predators. But now other researchers say their computer modeling shows that Apatosaurus’ tail wasn’t structurally strong enough to sustain a supersonic crack.

“Such an elongated and slender structure would allow achieving tip velocities in the order of 30 m/s, or 100 km/h [62 mph], far slower than the speed of sound,” a team led by Simone Conti of Portugal’s NOVA School of Science and Technology asserted this week in Scientific Reports.

Suffice it to say that Myhrvold isn’t convinced. “Their model is a joke,” he told GeekWire in an email. “They made a model that had a low maximum speed, in the motion they tried. They didn’t move the tail in the correct manner. … This is very much like saying, ‘Gee, I bought a bullwhip and wiggled it, but didn’t hear a crack, so that refutes that bullwhips can crack!’”

So it sounds as if the speed of a dinosaur’s tail will continue to be under dispute. Let’s just hope dueling paleontologists don’t pull out the bullwhips.