And like natural selection, it means that females choose traits in males that make survival of their offspring more likely.
就像自然选择一样，也就是说雌性选择雄性身上能使后代存活机率更大的特质。
Multiply those choices over thousands of generations, eventually,
把这些几千代所做的选择融合起来，最终，
Deinonychus' slashing claw gets sharper, faster, and more lethal.
恐爪龙凌厉的爪子变得更锋利，更快也更致命。
Triceratops' horn gets longer, and its shield grows tougher.
三角龙的角变得更长，盔甲也变得更坚韧。
And Parasaurolophus' crest becomes more advanced and their communication skills better and better.
副栉龙的头冠更加发达，沟通技巧也越加娴熟。
For Parasaurolophus, a female's concern during the breeding season would mostly be checking out the guys...
对于副栉龙，雌性在繁殖期最关心的就是审视雄性恐龙，
that is, finding which ones seem to be the healthiest and therefore were potentially the best fathers of the next generation.
也就是寻找那些看上去最健康也是最有可能成为下一代父亲的雄性恐龙。
Evolution perfects not only Parasaurolophus' ability to make sounds.
进化不仅使副栉龙在发声能力上趋近完美。
It also selects for genes that improve the ability to hear and interpret those sounds.
也对听觉和声波转化基因进行了选择。
Various male Parasaurolophus would presumably be making very loud, very raucous calls of a very particular sort,
大量雄性副栉龙可能会以特别的方式发出响亮刺耳的呼唤，
and the female Parasaurolophus would be judging the quality of that call...probably its sound,
雌性副栉龙会可能会根据声音判断信号的质量，
which may have represented how healthy the individual was, and its ability to be precise in terms of generating that sound,
这可能反映了个体的健康程度，还有准确发出该声音的能力，
because it showed that was a creature with a healthy mind, with all the proper genes for a good Parasaurolophus.
因为这表明了副栉龙拥有健康的头脑还有合适的基因。
Males with the largest crests can produce the richest and lowest frequencies...sounds that can travel for miles.
头冠最大的雄性可以发出最丰富和最低频的声波这些声波可以传递数英里。
Those same low-frequency calls become highly attractive to females.
这些低频的呼喊对雌性的吸引力很大。
We would have different Parasaurolophus competing with each other with these sound calls,
不同的副栉龙通过发声和同类竞争
and the females probably calling on occasion to say,
雌性可能偶尔会回应
"Hey, baby, that sounds really good. You're the one for me."
"嗨，宝贝，那声音真好听。你就是我的真命天子。"
For Parasaurolophus, genetic modifications over time give them the tools both to pick up and emit these low-frequency sounds.
对副栉龙来说，长期的基因变化使它们拥有了学习和模仿这些低频声音的工具。
In fact, over time, they evolve the ability to send and receive extremely low-frequency vibrations called infrasound.
事实上，在漫长的岁月中，它们进化出了收发一种叫做次声波的超低频振动的能力。
Each species seems to have had its own note or series of notes.
每个物种都有自己特殊的一系列音符。
You can have up to five different species of duckbill living in one place at one time,
你可以让五种不同的鸭嘴兽同时居住在一个地方，
so in the breeding season, you'd hear five different orchestras, five different ranges of courtship note.
那么在繁殖期你会听到五种不同的管弦乐，五种不同的求爱音符。
And you'd feel them through your feet, too, as they go into those really deep notes.
当它们发出这些低音时，你的双脚都能感受到。
But Parasaurolophus is the exception to the rule.
但副栉龙是个例外。
