This... 这个时代

134. saw Lystrosaurus go from total domination of the planet
     使地球的主宰者水龙兽
135. to extinction.
     走向灭绝
136. The mammals had lost their crown.
     哺乳动物走下王座
137. This...
     这个时代
138. ...was the age of reptiles.
     属于爬行动物
139. Today, there are more than 10,000 species of reptile...
     如今有超过一万种爬行动物
140. although they are not all as terrifying as their ancestors.
     虽然它们并非都像祖先那般可怕

来自《我们星球上的生命 第一季 第四集 Life on Our Planet S01E04 冷血动物》第 137 行