Question

When did the mass extinction occur? (Name the era and period)

Answer 1

at the beginning of this era

Step-by-step explanation:

Answer 2

Step-by-step explanation:

The first mass extinction is called the Ordovician-Silurian Extinction. It occurred about 440 million years ago, at the end of the period that paleontologists and geologists call the Ordovician, and followed by the start of the Silurian period. In this extinction event, many small organisms of the sea became extinct.