These are the cities that quite literally mark the boundary of the North American frontier.

这些城市实际上标志着北美边境的边界。

Dinosaurs like Allosaurus and Tyrannosaurus-Rex would've marked the boundaries of their territory with scent marks like modern predators do.

像异特龙和霸王龙这样的恐龙会像现代掠食者那样用气味在领地边缘做标记。

A few steps further on, a neat line of small bushes marked the boundary of the Villa grounds.

再往前走几步， 一排整齐的小灌木丛标志着别墅场地的边界。