In North America's deserts, water is pretty scarce, which is a challenge for plants with shallow roots.

在北美的沙漠中，水非常稀缺，这对根系较浅的植物来说是一个挑战。

And they also had much shallower anchoring roots than today's trees.

而且它们的锚固根也比今天的树浅得多。