The talented 20-year-old elephant, Angus, who helped Dr. Sereno. Angus is under the care of gifted animal trainer Michael Hackenberger.

Why compare Jobaria to an elephant?

Elephants rear on their hind limbs occasionally in the wild. They perform this feat regularly in captivity. By studying how an elephant rears on it's hind legs, Dr. Sereno hoped to better understand how Jobaria would stand on it's hind legs.

To rear up and to hold a hind leg stand, the center of mass of the elephant (or of Jobaria) must be balanced over the hind limbs.

But where is the center of mass of an elephant? No one had ever measured this directly. To determine the elephant's center of mass, Dr. Sereno needed to find out how much weight was on the forelimbs vs. the hind limbs of an elephant.

That's when Dr. Sereno decided to weigh Angus the elephant. At 12,800 pounds, Angus is the largest African elephant in captivity. He resides at the Bowmanville Zoo, just outside Toronto, Canada.

But where do you weigh an elephant?