Eugene Lew, age 11, of Berkeley, Calif., for his question:

How much did a Brontasaurus weigh?

We have no way of getting the exact weight of a brontasaurus. The last of these massive dinosaurs said goodbye to the world millions of years ago. Fossil bones and even complete skeletons of these monsters have been discovered. It is possible to gauge the size of this, one of the largest of the dinosaurs. From the weight of the bones and the estimated size it is possible to make a good guess of his weight while he was alive.

The most up‑to‑date guess puts his weight between 30 and 40 tons. Our biggest elephant, largest of the modern land animals, weighs around six tons. But Big Bronty was a featherweight when compared with our modern blue whale, One of these sea‑going monsters is three times the weight of old brontasaurus.