Ozone depletion may have sparked prehistoric extinction event: study

A study published in Science Advances suggests that UV ray exposure 358 million years ago may have triggered a mass extinction of ancient fish and plants. Researchers analyzed a 6-meter-long mudstone core from Greenland, finding fossilized spores that transitioned from healthy to malformed, indicating DNA damage from UV-B rays. This event marked the second mass extinction in the Devonian period, leading to the disappearance of many species, including giant armored sharks. The extinction also wiped out early land-venturing fish, paving the way for five-toed tetrapods to become the precursors of modern land animals.

What does the study suggest about the parent plants based on the spores?

What was the significance of the 2nd mass extinction in relation to land animals?