By contrast, the biggest mammal that ever walked on land was the hornless rhinoceros known as Paraceratherium.

相比之下，曾经在陆地上行走过的最大的哺乳动称为 Paraceratherium 的无角犀牛。

Some male tunnelers avoid the fray by masquerading as hornless females and sneaking into tunnels to mate while the guardians' heads are turned.

一些雄性挖道蜣螂会扮无角雌蜣螂来避免争斗，并在守卫蜣螂不注意时，悄悄溜通道行交配。

But there were abundant remains of one species of dinosaur from the same fossil formation: Protoceratops, a small, hornless ceratopsian.

但，同一化石地层中有一种恐龙的大量遗骸：原角龙，一种小型无角角龙。

Some male tunnelers avoid the fray by masquerading as hornless females and sneaking into tunnels to mate while the guardians’ heads are turned.

一些雄性地道掘地者伪有角的雌性，并在守卫者转过头的时候潜入地道交配，从而避免了争斗。

Some places are so desperate to protect their rhinos that they will tranquilize them and carefully remove their horns in the hope that poachers will leave these hornless rhinos alone.

有些地方为了保护犀牛，孤注一掷，他们会麻醉犀牛，然后小心翼翼地取走犀牛角，希望偷猎者能放过这些无角犀牛。

This year, scientists cloned pigs, dogs, mules and monkeys, and gene editing techniques are now being used to create designer animals, like these Holsteins genetically engineered to be hornless.

今年，科学家们克隆了猪、狗、骡子和猴子，基因编辑技术现在用来创造设计动， 比如这些经过基因改造而有角的荷斯坦牛。