Question

PLLLZ HELP This graph best represents the populations of marine groups before and after the

Cambrian explosion

Ordovician extinction

Permo-Triassic Extinction Event

Alleghenian Orogeny

Answer 1

Ordovician extinction .

Step-by-step explanation:

The Ordovician extinction was an event that occurred around 450 million years ago and caused the disappearance of 60% of marine species.

This event was caused by global cooling which resulted in the drop of the sea level. This change mostly affected the species that developed life in the deep, depriving them of their natural habitat.