Without warm summers to melt them, 没有了温暖的夏季将其融化
they need little energy to keep warm... 所以它们不需要多少能量 就能保持温暖
it has been too warm for ice to form. 温度都太高 无法形成冰冻
At these altitudes, mammals must feed regularly to keep warm. 海拔如此之高 哺乳动物必须定时进食以保持体温
the warm, wet conditions in which they had thrived began to change. 曾令它们兴旺发展的暖湿条件 开始发生变化
Like most reptiles, they must bask in the sun to warm up. 与多数爬行动物一样 它们必须晒太阳以保暖
Feathers, that first evolved to keep dinosaurs warm, 羽毛最初进化是为帮助恐龙保暖
These survivors were kept warm by feathers... 这些幸存者靠羽毛保暖