was one reason terror birds went extinct. 是骇鸟灭绝的原因之一

137. With nothing to separate them, a fight is inevitable.
     没有东西将它们隔离 大战不可避免
138. But they have company.
     但现场不仅有它们
139. The Smilodon's mammalian cunning
     刃齿虎作为哺乳动物的狡黠
140. was one reason terror birds went extinct.
     是骇鸟灭绝的原因之一
141. Competition, both within and between species,
     物种内及物种间的竞争
142. has always driven evolution.
     一直推动着进化
143. But it's not just those doing battle that are always changing.
     但不断变化的 不仅仅是参与战斗的生物

来自《我们星球上的生命 第一季 第一集 Life on Our Planet S01E01 生命法则》第 140 行