【英语时差8,16】食肉鲸和食素鲸（上）

Everyone is familiar with the riddle¹: Which came first, the chicken or the egg? This sometimes leads to discussions about bird evolution. But most people don’t realize this type of question is common in paleontology. For example: Which came first, the meat-eating whale ancestor or the plant-eating one? Answering that question has not been easy. Early fossil finds suggested whales might be related to the mesonychids, an extinct group of wolf sized, hoof² toed carnivores. These mammals had triangular³ teeth similar to whales. But when genetic⁴ analysis began, that idea was put to the test. You see, scientists comparing DNA⁵ of whales to other mammals found that whales were most closely related to plant eating ungulates. This group includes sheep, antelopes⁶ and pigs. As a matter of fact, the closest living relative to whales is the hippopotamus⁷. So, how is it that modern whales are meat eaters?

1 riddle   

n.谜，谜语，粗筛；vt.解谜，给…出谜，筛，检查，鉴定，非难，充满于；vi.出谜

参考例句：

• The riddle couldn't be solved by the child.这个谜语孩子猜不出来。
• Her disappearance is a complete riddle.她的失踪完全是一个谜。

2 hoof   

n.(马，牛等的)蹄

参考例句：

• Suddenly he heard the quick,short click of a horse's hoof behind him.突然间，他听见背后响起一阵急骤的马蹄的得得声。
• I was kicked by a hoof.我被一只蹄子踢到了。

3 triangular   

adj.三角（形）的，三者间的

参考例句：

• It's more or less triangular plot of land.这块地略成三角形。
• One particular triangular relationship became the model of Simone's first novel.一段特殊的三角关系成了西蒙娜第一本小说的原型。

4 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

5 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

6 antelopes   

羚羊( antelope的名词复数 )； 羚羊皮革

参考例句：

• One jump, and you're out, and we'll run for it like antelopes.' 你只要一跳就出来了，我们可以像羚羊那样飞快地逃掉。”
• Most antelopes can withhold their young for weeks, even months. 绝大部分羚羊能把分娩期推迟几个星期，甚至几个月。

7 hippopotamus   

n.河马

参考例句：

• The children enjoyed watching the hippopotamus wallowing in the mud.孩子们真喜观看河马在泥中打滚。
• A hippopotamus surfs the waves off the coast of Gabon.一头河马在加蓬的海岸附近冲浪。