Q: Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the "Age of Fish". The first ray-finned and lobe-finned bony fish appeared, while the placoderms began dominating almost every known aquatic environment. The ancestors of all four-limbed vertebrates (tetrapods) began adapting to walking on land, as their strong pectoral and pelvic fins gradually evolved into legs. In the oceans, primitive sharks became more numerous than in the Silurian and Late Ordovician.

Answer this question: which period is known as the age of the fishes?
A: the Devonian
Explain how we arrive at this answer:
Explanation: The important part for answering this question is: Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the "Age of Fish".