prehistoric

考古学家发现了许多史前动物的化石。

Archaeologists have found many fossils of ___prehistoric animals.

洞穴壁画为我们提供了关于史前人类生活的重要线索。

Cave paintings offer important clues about ___prehistoric human life.

这家公司还在用纸质文件办公，真是老掉牙了。

This company still uses paper files for work—it's downright ___prehistoric.