The result, once natural selection had done its work over the course of millions of years, was the now familiar cast of Allosaurus and Tyrannosaurus rex.
结果，历经数百万年间的自然选择，形成了我们今日熟知的异特龙和雷克斯霸王龙族群。
The Allosaurus was a meat eater.
异特龙是肉食动物。
The Allosaurus walked on two feet, but was slow. The Allosaurus could run.
