复习
Determining what extinct dinosaurs ate is difficult, but we can infer some aspects of their dietary preferences.
要确定已经灭绝的恐龙吃什么比较困难，但是我们可以推测出它们喜欢吃什么食物。
Traditionally this information has been derived from direct evidence, such as stomach contents, and indirect evidence, such as establishing a correlation between particular body characteristics and diets of living animals and then inferring habits for dinosaurs.
传统上而言，这些信息来自于直接证据，比如胃里的食物，以及间接证据，比如通过恐龙特别的身体特征和现今存活的动物的饮食习惯之间建立关系来推断恐龙的饮食习惯。
Animals such as house cats and dogs have large, stabbing canine teeth at the front of the mouth and smaller, equally sharp teeth farther back in their jaws.
比如家养的猫和狗这类动物，嘴前部有着尖锐的犬牙，而且后颌有着小一些但同样尖锐的牙齿。
Many of these animals are also armed with sharp claws.
而且大多数这类动物都有着锋利的爪子。
The advantage of teeth and claws as predatory tools is obvious.
牙齿和爪子作为捕食工具的优势非常明显。
Now consider animals like cows, horses, rabbits, and mice.
然后再看牛、马、兔子和老鼠这些动物。
These animals have flat teeth at the back of the jaw that are analogous to and have the samefunction as grindstones.
它们后颌的牙齿扁平，功能类似于磨石。
Unlike the meat-slicing and stabbing teeth of carnivores, the teeth of these animals grind and shred plant material before digestion.
和食肉动物用于撕碎肉类的利牙不同，这些动物的牙齿会将植物磨碎再消化。