wildlife populations have fallen by an average of almost 70%, 野生动物种群就已平均下降将近70%
Their best defense is to keep an eye on the danger, 它们最好的防御是警惕危险
an unbroken line of ancestry stretching back four billion years 一条绵延40亿年的连续谱系
and quickly became home to an incredible wealth of animal life. 很快成为大批动物的家园
all that remains is an eerie silence. 只剩下一片诡异的寂静
the megaflood smashes an 800-kilometer-long path through the American continent, 大洪水在美洲大♥陆♥上 形成了800公里长的通道
In North America, the meltwater formed an enormous glacial lake 在北美 融水形成一个巨大的冰川湖
This is the flip side of an ice age. 这是冰河时代的另一面