For years now, paleontologists have been debating about how gigantic plant-eating dinosaurs, known as sauropods, held their long necks. Could they stretch their tall necks upright, as giraffes do today, or did they hold them horizontally, more parallel to the ground?

Other scientists have since run with that comparison to canister-style vacuum cleaners and have set out to prove or disprove it. Most recently, evolutionary ecologists Graeme Ruxton of the University of Glasgow and David Wilkinson of Liverpool John Moores University developed a mathematical model to virtually test how dinosaurs such as Brachiosaurus, with its near 30-foot-long neck, moved.

The researchers took into account not only this neck length, but also the weight (over 120,000 pounds) and body measurement—comparable to three school buses—for Brachiosaurus. The scientists also plugged in the numbers for Apatosaurus, another huge plant-eating dinosaur....