Back in the 1990s, scientists found lots of plant spores in rocks from Saudi Arabia and the Czech Republic.

早在 20 世纪 90 年代，科学家就在沙特阿拉伯和捷克共和国的岩石中发现了大量植物孢子。

And they could tell they came from land plants, and not aquatic plants, because the spores had a thick covering that all land plant spores have today.

他们可以看出它们来自陆生植物，而不是水生植物， 因为孢子有一层厚厚的覆盖物， 今天所有的陆生植物孢子都有。