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Over 120 million years, the ozone layer gets thicker and prevents more and more radiation from reaching the Earth's surface.
1亿2000万年下来，臭氧层渐渐变厚，拦住更多辐射，不让他们到达地球表面。
Without this layer,
没这层臭氧，
life on land simply wouldn't exist.
陆地就不会有生命。
Now, shielded from radiation, life takes off.
不受辐射伤害的生命蓬勃发展，
Small mossy lumps are the first land plants.
这些小苔藓团是最早的陆地植物。
They pump out even more oxygen.
它们释放更多的氧，
Levels soar.
氧浓度激增。
375 million years ago, a new species lives in the water, swimming.
3亿7500万年前，水里有种东西在游泳，
It's a strange fish called a Tiktaalik.
这是名为提塔利克鱼的怪鱼。
It uses its neck to raise itself up.
它可以挺起脖子，
And its fins function as legs,
把鳍当成腿，
allowing it to move out of the water.
从水里走上岸。
