form some of the largest herds the Earth had ever seen. 形成了地球史上最大的兽群

221. ...but they had evolved jaws that could chew.
     但它们已经进化出能够咀嚼的颌部
222. Combined with the surge in plant life,
     再加上植物的激增
223. this saw ornithischians, like Maiasaura,
     导致慈母龙这样的鸟臀
224. form some of the largest herds the Earth had ever seen.
     形成了地球史上最大的兽群
225. Across the world, dinosaurs now dominated
     现在恐龙在全球各地
226. every land habitat the changing planet had to offer.
     主宰每一片陆地栖息地
227. But at the same time...
     但是与此同时

来自《我们星球上的生命 第一季 第五集 Life on Our Planet S01E05 巨兽阴影下》第 224 行