单选题 More clues exist in other parts of the skull. The jaw joint of carnivores such as dogs and cats has the mechanical advantage of being at the same level as the tooth row, allowing the jaws to close with tremendous speed and forcing the upper teeth to occlude against the lower teeth with great precision. In herbivorous animals, rapid jaw closure is less important. Because the flat teeth of herbivores work like grindstones; however, the jaws must move both side to side and front to back. The jaw joint of many advanced herbivores, such as cows, lies at a different level than the tooth row, allowing transverse tearing, shredding, and compression of plant material. If we extend such observations to extinct dinosaurs, we can infer dietary preferences (such as carnivory and herbivory), even though we cannot determine the exact diet. The duck-billed dinosaurs known as hadrosaurs are a good example of a group whose jaw joint is below the level of the tooth row, which probably helped them grind up tough, fibrous vegetation. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.