What Did Fish Evolve From

Later, about 420 million years ago, the jawed fish evolved from one of the ostracoderms. After the appearance of jawed fish, most ostracoderm species underwent a decline, and the last ostracoderms became extinct at the end of the Devonian period.

Where did fishes evolve from?

Fish first evolved in the sea. The oceans have been teeming with them for almost half a billion years, so there is no reason to doubt that the fish living there today did all their evolving in salt water – until you take a closer look at their family tree.

What was the first fish to evolve?

The first fish were primitive jawless forms (agnathans) which appeared in the Early Cambrian, but remained generally rare until the Silurian and Devonian when they underwent a rapid evolution.