This skull belongs to the bizarre-looking saiga antelope, one of the less familiar faces of the ice age scene. Like the musk ox, saiga have a thick winter coat of hollow hairs for extra insulation. But they have another adaptation all of their own, an enormous bulbous nose. The nose is shaped like this because it contains large air sacs which pre-warm cold air while breathing in and retain precious moisture before breathing out. So saiga, too, were well-equipped to live in the cold, dry climate of Beringia. Today they’re only found in another bleak environment, the steppes of central Asia.
Some ice age animals took a totally different approach to surviving the winter. Arctic ground squirrels feed up in autumn, building up as much body fat as possible, and almost doubling their weight. As the first snows fall, they retreat to their underground burrows and bypass the winter entirely.
1 skull
n.头骨;颅骨
参考例句：
The skull bones fuse between the ages of fifteen and twenty-five.头骨在15至25岁之间长合。
He fell out of the window and cracked his skull.他从窗子摔了出去，跌裂了颅骨。
2 antelope
n.羚羊;羚羊皮
参考例句：
Choosing the antelope shows that China wants a Green Olympics.选择藏羚羊表示中国需要绿色奥运。
The tiger was dragging the antelope across the field.老虎拖着羚羊穿过原野。
3 musk
n.麝香, 能发出麝香的各种各样的植物，香猫
参考例句：
Musk is used for perfume and stimulant.麝香可以用作香料和兴奋剂。
She scented her clothes with musk.她用麝香使衣服充满了香味。
4 insulation
n.隔离;绝缘;隔热
参考例句：
Please examine the insulation of the electric wires in my house.请检查一下我屋子里电线的绝缘情况。
It is always difficult to assure good insulation between the electric leads.要保证两个电触头之间有良好的绝缘总是很困难的。
5 bleak
adj.(天气)阴冷的;凄凉的;暗淡的
参考例句：
They showed me into a bleak waiting room.他们引我来到一间阴冷的会客室。
The company's prospects look pretty bleak.这家公司的前景异常暗淡。
6 burrows
n.地洞( burrow的名词复数 )v.挖掘(洞穴)，挖洞( burrow的第三人称单数 );翻寻
参考例句：
The intertidal beach unit contains some organism burrows. 潮间海滩单元含有一些生物潜穴。 来自辞典例句
A mole burrows its way through the ground. 鼹鼠会在地下钻洞前进。 来自辞典例句
7 entirely
ad.全部地，完整地;完全地，彻底地
参考例句：
The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
His life was entirely given up to the educational work. 他的一生统统献给了教育工作。
